mirror of https://github.com/FFmpeg/FFmpeg.git
* qatar/master: Add an audio transcoding example. Conflicts: configure doc/Makefile Merged-by: Michael Niedermayer <michaelni@gmx.at>pull/49/head
commit
715f3623f8
3 changed files with 773 additions and 1 deletions
@ -0,0 +1,769 @@ |
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/*
|
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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|
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/**
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* @file simple audio converter |
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* Convert an input audio file to AAC in an MP4 container using Libav. |
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* @author Andreas Unterweger (dustsigns@gmail.com) |
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*/ |
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|
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#include <stdio.h> |
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#include "libavformat/avformat.h" |
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#include "libavformat/avio.h" |
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|
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#include "libavcodec/avcodec.h" |
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|
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#include "libavutil/audio_fifo.h" |
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#include "libavutil/avstring.h" |
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#include "libavutil/frame.h" |
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#include "libavutil/opt.h" |
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|
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#include "libavresample/avresample.h" |
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|
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/** The output bit rate in kbit/s */ |
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#define OUTPUT_BIT_RATE 48000 |
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/** The number of output channels */ |
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#define OUTPUT_CHANNELS 2 |
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/** The audio sample output format */ |
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#define OUTPUT_SAMPLE_FORMAT AV_SAMPLE_FMT_S16 |
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|
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/**
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* Convert an error code into a text message. |
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* @param error Error code to be converted |
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* @return Corresponding error text (not thread-safe) |
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*/ |
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static char *const get_error_text(const int error) |
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{ |
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static char error_buffer[255]; |
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av_strerror(error, error_buffer, sizeof(error_buffer)); |
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return error_buffer; |
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} |
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|
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/** Open an input file and the required decoder. */ |
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static int open_input_file(const char *filename, |
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AVFormatContext **input_format_context, |
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AVCodecContext **input_codec_context) |
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{ |
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AVCodec *input_codec; |
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int error; |
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|
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/** Open the input file to read from it. */ |
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if ((error = avformat_open_input(input_format_context, filename, NULL, |
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NULL)) < 0) { |
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fprintf(stderr, "Could not open input file '%s' (error '%s')\n", |
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filename, get_error_text(error)); |
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*input_format_context = NULL; |
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return error; |
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} |
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|
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/** Get information on the input file (number of streams etc.). */ |
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if ((error = avformat_find_stream_info(*input_format_context, NULL)) < 0) { |
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fprintf(stderr, "Could not open find stream info (error '%s')\n", |
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get_error_text(error)); |
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avformat_close_input(input_format_context); |
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return error; |
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} |
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|
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/** Make sure that there is only one stream in the input file. */ |
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if ((*input_format_context)->nb_streams != 1) { |
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fprintf(stderr, "Expected one audio input stream, but found %d\n", |
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(*input_format_context)->nb_streams); |
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avformat_close_input(input_format_context); |
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return AVERROR_EXIT; |
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} |
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|
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/** Find a decoder for the audio stream. */ |
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if (!(input_codec = avcodec_find_decoder((*input_format_context)->streams[0]->codec->codec_id))) { |
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fprintf(stderr, "Could not find input codec\n"); |
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avformat_close_input(input_format_context); |
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return AVERROR_EXIT; |
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} |
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|
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/** Open the decoder for the audio stream to use it later. */ |
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if ((error = avcodec_open2((*input_format_context)->streams[0]->codec, |
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input_codec, NULL)) < 0) { |
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fprintf(stderr, "Could not open input codec (error '%s')\n", |
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get_error_text(error)); |
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avformat_close_input(input_format_context); |
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return error; |
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} |
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|
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/** Save the decoder context for easier access later. */ |
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*input_codec_context = (*input_format_context)->streams[0]->codec; |
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return 0; |
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} |
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|
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/**
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* Open an output file and the required encoder. |
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* Also set some basic encoder parameters. |
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* Some of these parameters are based on the input file's parameters. |
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*/ |
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static int open_output_file(const char *filename, |
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AVCodecContext *input_codec_context, |
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AVFormatContext **output_format_context, |
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AVCodecContext **output_codec_context) |
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{ |
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AVIOContext *output_io_context = NULL; |
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AVStream *stream = NULL; |
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AVCodec *output_codec = NULL; |
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int error; |
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|
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/** Open the output file to write to it. */ |
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if ((error = avio_open(&output_io_context, filename, |
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AVIO_FLAG_WRITE)) < 0) { |
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fprintf(stderr, "Could not open output file '%s' (error '%s')\n", |
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filename, get_error_text(error)); |
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return error; |
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} |
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|
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/** Create a new format context for the output container format. */ |
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if (!(*output_format_context = avformat_alloc_context())) { |
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fprintf(stderr, "Could not allocate output format context\n"); |
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return AVERROR(ENOMEM); |
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} |
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|
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/** Associate the output file (pointer) with the container format context. */ |
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(*output_format_context)->pb = output_io_context; |
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|
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/** Guess the desired container format based on the file extension. */ |
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if (!((*output_format_context)->oformat = av_guess_format(NULL, filename, |
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NULL))) { |
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fprintf(stderr, "Could not find output file format\n"); |
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goto cleanup; |
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} |
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|
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av_strlcpy((*output_format_context)->filename, filename, |
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sizeof((*output_format_context)->filename)); |
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|
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/** Find the encoder to be used by its name. */ |
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if (!(output_codec = avcodec_find_encoder(AV_CODEC_ID_AAC))) { |
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fprintf(stderr, "Could not find an AAC encoder.\n"); |
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goto cleanup; |
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} |
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|
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/** Create a new audio stream in the output file container. */ |
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if (!(stream = avformat_new_stream(*output_format_context, output_codec))) { |
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fprintf(stderr, "Could not create new stream\n"); |
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error = AVERROR(ENOMEM); |
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goto cleanup; |
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} |
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|
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/** Save the encoder context for easiert access later. */ |
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*output_codec_context = stream->codec; |
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/**
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* Set the basic encoder parameters. |
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* The input file's sample rate is used to avoid a sample rate conversion. |
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*/ |
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(*output_codec_context)->channels = OUTPUT_CHANNELS; |
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(*output_codec_context)->channel_layout = av_get_default_channel_layout(OUTPUT_CHANNELS); |
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(*output_codec_context)->sample_rate = input_codec_context->sample_rate; |
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(*output_codec_context)->sample_fmt = AV_SAMPLE_FMT_S16; |
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(*output_codec_context)->bit_rate = OUTPUT_BIT_RATE; |
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|
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/**
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* Some container formats (like MP4) require global headers to be present |
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* Mark the encoder so that it behaves accordingly. |
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*/ |
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if ((*output_format_context)->oformat->flags & AVFMT_GLOBALHEADER) |
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(*output_codec_context)->flags |= CODEC_FLAG_GLOBAL_HEADER; |
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|
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/** Open the encoder for the audio stream to use it later. */ |
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if ((error = avcodec_open2(*output_codec_context, output_codec, NULL)) < 0) { |
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fprintf(stderr, "Could not open output codec (error '%s')\n", |
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get_error_text(error)); |
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goto cleanup; |
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} |
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return 0; |
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cleanup: |
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avio_close((*output_format_context)->pb); |
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avformat_free_context(*output_format_context); |
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*output_format_context = NULL; |
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return error < 0 ? error : AVERROR_EXIT; |
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} |
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|
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/** Initialize one data packet for reading or writing. */ |
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static void init_packet(AVPacket *packet) |
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{ |
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av_init_packet(packet); |
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/** Set the packet data and size so that it is recognized as being empty. */ |
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packet->data = NULL; |
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packet->size = 0; |
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} |
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|
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/** Initialize one audio frame for reading from the input file */ |
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static int init_input_frame(AVFrame **frame) |
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{ |
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if (!(*frame = av_frame_alloc())) { |
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fprintf(stderr, "Could not allocate input frame\n"); |
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return AVERROR(ENOMEM); |
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} |
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return 0; |
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} |
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|
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/**
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* Initialize the audio resampler based on the input and output codec settings. |
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* If the input and output sample formats differ, a conversion is required |
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* libavresample takes care of this, but requires initialization. |
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*/ |
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static int init_resampler(AVCodecContext *input_codec_context, |
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AVCodecContext *output_codec_context, |
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AVAudioResampleContext **resample_context) |
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{ |
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/**
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* Only initialize the resampler if it is necessary, i.e., |
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* if and only if the sample formats differ. |
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*/ |
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if (input_codec_context->sample_fmt != output_codec_context->sample_fmt || |
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input_codec_context->channels != output_codec_context->channels) { |
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int error; |
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|
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/** Create a resampler context for the conversion. */ |
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if (!(*resample_context = avresample_alloc_context())) { |
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fprintf(stderr, "Could not allocate resample context\n"); |
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return AVERROR(ENOMEM); |
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} |
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|
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/**
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* Set the conversion parameters. |
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* Default channel layouts based on the number of channels |
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* are assumed for simplicity (they are sometimes not detected |
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* properly by the demuxer and/or decoder). |
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*/ |
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av_opt_set_int(*resample_context, "in_channel_layout", |
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av_get_default_channel_layout(input_codec_context->channels), 0); |
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av_opt_set_int(*resample_context, "out_channel_layout", |
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av_get_default_channel_layout(output_codec_context->channels), 0); |
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av_opt_set_int(*resample_context, "in_sample_rate", |
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input_codec_context->sample_rate, 0); |
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av_opt_set_int(*resample_context, "out_sample_rate", |
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output_codec_context->sample_rate, 0); |
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av_opt_set_int(*resample_context, "in_sample_fmt", |
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input_codec_context->sample_fmt, 0); |
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av_opt_set_int(*resample_context, "out_sample_fmt", |
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output_codec_context->sample_fmt, 0); |
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|
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/** Open the resampler with the specified parameters. */ |
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if ((error = avresample_open(*resample_context)) < 0) { |
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fprintf(stderr, "Could not open resample context\n"); |
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avresample_free(resample_context); |
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return error; |
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} |
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} |
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return 0; |
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} |
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|
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/** Initialize a FIFO buffer for the audio samples to be encoded. */ |
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static int init_fifo(AVAudioFifo **fifo) |
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{ |
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/** Create the FIFO buffer based on the specified output sample format. */ |
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if (!(*fifo = av_audio_fifo_alloc(OUTPUT_SAMPLE_FORMAT, OUTPUT_CHANNELS, 1))) { |
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fprintf(stderr, "Could not allocate FIFO\n"); |
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return AVERROR(ENOMEM); |
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} |
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return 0; |
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} |
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|
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/** Write the header of the output file container. */ |
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static int write_output_file_header(AVFormatContext *output_format_context) |
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{ |
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int error; |
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if ((error = avformat_write_header(output_format_context, NULL)) < 0) { |
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fprintf(stderr, "Could not write output file header (error '%s')\n", |
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get_error_text(error)); |
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return error; |
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} |
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return 0; |
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} |
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|
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/** Decode one audio frame from the input file. */ |
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static int decode_audio_frame(AVFrame *frame, |
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AVFormatContext *input_format_context, |
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AVCodecContext *input_codec_context, |
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int *data_present, int *finished) |
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{ |
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/** Packet used for temporary storage. */ |
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AVPacket input_packet; |
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int error; |
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init_packet(&input_packet); |
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|
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/** Read one audio frame from the input file into a temporary packet. */ |
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if ((error = av_read_frame(input_format_context, &input_packet)) < 0) { |
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/** If we are the the end of the file, flush the decoder below. */ |
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if (error == AVERROR_EOF) |
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*finished = 1; |
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else { |
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fprintf(stderr, "Could not read frame (error '%s')\n", |
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get_error_text(error)); |
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return error; |
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} |
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} |
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|
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/**
|
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* Decode the audio frame stored in the temporary packet. |
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* The input audio stream decoder is used to do this. |
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* If we are at the end of the file, pass an empty packet to the decoder |
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* to flush it. |
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*/ |
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if ((error = avcodec_decode_audio4(input_codec_context, frame, |
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data_present, &input_packet)) < 0) { |
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fprintf(stderr, "Could not decode frame (error '%s')\n", |
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get_error_text(error)); |
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av_free_packet(&input_packet); |
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return error; |
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} |
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|
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/**
|
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* If the decoder has not been flushed completely, we are not finished, |
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* so that this function has to be called again. |
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*/ |
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if (*finished && *data_present) |
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*finished = 0; |
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av_free_packet(&input_packet); |
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return 0; |
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} |
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|
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/**
|
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* Initialize a temporary storage for the specified number of audio samples. |
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* The conversion requires temporary storage due to the different format. |
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* The number of audio samples to be allocated is specified in frame_size. |
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*/ |
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static int init_converted_samples(uint8_t ***converted_input_samples, |
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AVCodecContext *output_codec_context, |
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int frame_size) |
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{ |
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int error; |
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|
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/**
|
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* Allocate as many pointers as there are audio channels. |
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* Each pointer will later point to the audio samples of the corresponding |
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* channels (although it may be NULL for interleaved formats). |
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*/ |
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if (!(*converted_input_samples = calloc(output_codec_context->channels, |
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sizeof(**converted_input_samples)))) { |
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fprintf(stderr, "Could not allocate converted input sample pointers\n"); |
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return AVERROR(ENOMEM); |
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} |
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|
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/**
|
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* Allocate memory for the samples of all channels in one consecutive |
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* block for convenience. |
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*/ |
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if ((error = av_samples_alloc(*converted_input_samples, NULL, |
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output_codec_context->channels, |
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frame_size, |
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output_codec_context->sample_fmt, 0)) < 0) { |
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fprintf(stderr, |
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"Could not allocate converted input samples (error '%s')\n", |
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get_error_text(error)); |
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av_freep(&(*converted_input_samples)[0]); |
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free(*converted_input_samples); |
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return error; |
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} |
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return 0; |
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} |
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|
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/**
|
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* Convert the input audio samples into the output sample format. |
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* The conversion happens on a per-frame basis, the size of which is specified |
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* by frame_size. |
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*/ |
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static int convert_samples(uint8_t **input_data, |
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uint8_t **converted_data, const int frame_size, |
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AVAudioResampleContext *resample_context) |
||||
{ |
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int error; |
||||
|
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/** Convert the samples using the resampler. */ |
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if ((error = avresample_convert(resample_context, converted_data, 0, |
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frame_size, input_data, 0, frame_size)) < 0) { |
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fprintf(stderr, "Could not convert input samples (error '%s')\n", |
||||
get_error_text(error)); |
||||
return error; |
||||
} |
||||
|
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/**
|
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* Perform a sanity check so that the number of converted samples is |
||||
* not greater than the number of samples to be converted. |
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* If the sample rates differ, this case has to be handled differently |
||||
*/ |
||||
if (avresample_available(resample_context)) { |
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fprintf(stderr, "Converted samples left over\n"); |
||||
return AVERROR_EXIT; |
||||
} |
||||
|
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return 0; |
||||
} |
||||
|
||||
/** Add converted input audio samples to the FIFO buffer for later processing. */ |
||||
static int add_samples_to_fifo(AVAudioFifo *fifo, |
||||
uint8_t **converted_input_samples, |
||||
const int frame_size) |
||||
{ |
||||
int error; |
||||
|
||||
/**
|
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* Make the FIFO as large as it needs to be to hold both, |
||||
* the old and the new samples. |
||||
*/ |
||||
if ((error = av_audio_fifo_realloc(fifo, av_audio_fifo_size(fifo) + frame_size)) < 0) { |
||||
fprintf(stderr, "Could not reallocate FIFO\n"); |
||||
return error; |
||||
} |
||||
|
||||
/** Store the new samples in the FIFO buffer. */ |
||||
if (av_audio_fifo_write(fifo, (void **)converted_input_samples, |
||||
frame_size) < frame_size) { |
||||
fprintf(stderr, "Could not write data to FIFO\n"); |
||||
return AVERROR_EXIT; |
||||
} |
||||
return 0; |
||||
} |
||||
|
||||
/**
|
||||
* Read one audio frame from the input file, decodes, converts and stores |
||||
* it in the FIFO buffer. |
||||
*/ |
||||
static int read_decode_convert_and_store(AVAudioFifo *fifo, |
||||
AVFormatContext *input_format_context, |
||||
AVCodecContext *input_codec_context, |
||||
AVCodecContext *output_codec_context, |
||||
AVAudioResampleContext *resampler_context, |
||||
int *finished) |
||||
{ |
||||
/** Temporary storage of the input samples of the frame read from the file. */ |
||||
AVFrame *input_frame = NULL; |
||||
/** Temporary storage for the converted input samples. */ |
||||
uint8_t **converted_input_samples = NULL; |
||||
int data_present; |
||||
int ret = AVERROR_EXIT; |
||||
|
||||
/** Initialize temporary storage for one input frame. */ |
||||
if (init_input_frame(&input_frame)) |
||||
goto cleanup; |
||||
/** Decode one frame worth of audio samples. */ |
||||
if (decode_audio_frame(input_frame, input_format_context, |
||||
input_codec_context, &data_present, finished)) |
||||
goto cleanup; |
||||
/**
|
||||
* If we are at the end of the file and there are no more samples |
||||
* in the decoder which are delayed, we are actually finished. |
||||
* This must not be treated as an error. |
||||
*/ |
||||
if (*finished && !data_present) { |
||||
ret = 0; |
||||
goto cleanup; |
||||
} |
||||
/** If there is decoded data, convert and store it */ |
||||
if (data_present) { |
||||
/** Initialize the temporary storage for the converted input samples. */ |
||||
if (init_converted_samples(&converted_input_samples, output_codec_context, |
||||
input_frame->nb_samples)) |
||||
goto cleanup; |
||||
|
||||
/**
|
||||
* Convert the input samples to the desired output sample format. |
||||
* This requires a temporary storage provided by converted_input_samples. |
||||
*/ |
||||
if (convert_samples(input_frame->extended_data, converted_input_samples, |
||||
input_frame->nb_samples, resampler_context)) |
||||
goto cleanup; |
||||
|
||||
/** Add the converted input samples to the FIFO buffer for later processing. */ |
||||
if (add_samples_to_fifo(fifo, converted_input_samples, |
||||
input_frame->nb_samples)) |
||||
goto cleanup; |
||||
ret = 0; |
||||
} |
||||
ret = 0; |
||||
|
||||
cleanup: |
||||
if (converted_input_samples) { |
||||
av_freep(&converted_input_samples[0]); |
||||
free(converted_input_samples); |
||||
} |
||||
av_frame_free(&input_frame); |
||||
|
||||
return ret; |
||||
} |
||||
|
||||
/**
|
||||
* Initialize one input frame for writing to the output file. |
||||
* The frame will be exactly frame_size samples large. |
||||
*/ |
||||
static int init_output_frame(AVFrame **frame, |
||||
AVCodecContext *output_codec_context, |
||||
int frame_size) |
||||
{ |
||||
int error; |
||||
|
||||
/** Create a new frame to store the audio samples. */ |
||||
if (!(*frame = av_frame_alloc())) { |
||||
fprintf(stderr, "Could not allocate output frame\n"); |
||||
return AVERROR_EXIT; |
||||
} |
||||
|
||||
/**
|
||||
* Set the frame's parameters, especially its size and format. |
||||
* av_frame_get_buffer needs this to allocate memory for the |
||||
* audio samples of the frame. |
||||
* Default channel layouts based on the number of channels |
||||
* are assumed for simplicity. |
||||
*/ |
||||
(*frame)->nb_samples = frame_size; |
||||
(*frame)->channel_layout = output_codec_context->channel_layout; |
||||
(*frame)->format = output_codec_context->sample_fmt; |
||||
(*frame)->sample_rate = output_codec_context->sample_rate; |
||||
|
||||
/**
|
||||
* Allocate the samples of the created frame. This call will make |
||||
* sure that the audio frame can hold as many samples as specified. |
||||
*/ |
||||
if ((error = av_frame_get_buffer(*frame, 0)) < 0) { |
||||
fprintf(stderr, "Could allocate output frame samples (error '%s')\n", |
||||
get_error_text(error)); |
||||
av_frame_free(frame); |
||||
return error; |
||||
} |
||||
|
||||
return 0; |
||||
} |
||||
|
||||
/** Encode one frame worth of audio to the output file. */ |
||||
static int encode_audio_frame(AVFrame *frame, |
||||
AVFormatContext *output_format_context, |
||||
AVCodecContext *output_codec_context, |
||||
int *data_present) |
||||
{ |
||||
/** Packet used for temporary storage. */ |
||||
AVPacket output_packet; |
||||
int error; |
||||
init_packet(&output_packet); |
||||
|
||||
/**
|
||||
* Encode the audio frame and store it in the temporary packet. |
||||
* The output audio stream encoder is used to do this. |
||||
*/ |
||||
if ((error = avcodec_encode_audio2(output_codec_context, &output_packet, |
||||
frame, data_present)) < 0) { |
||||
fprintf(stderr, "Could not encode frame (error '%s')\n", |
||||
get_error_text(error)); |
||||
av_free_packet(&output_packet); |
||||
return error; |
||||
} |
||||
|
||||
/** Write one audio frame from the temporary packet to the output file. */ |
||||
if (*data_present) { |
||||
if ((error = av_write_frame(output_format_context, &output_packet)) < 0) { |
||||
fprintf(stderr, "Could not write frame (error '%s')\n", |
||||
get_error_text(error)); |
||||
av_free_packet(&output_packet); |
||||
return error; |
||||
} |
||||
|
||||
av_free_packet(&output_packet); |
||||
} |
||||
|
||||
return 0; |
||||
} |
||||
|
||||
/**
|
||||
* Load one audio frame from the FIFO buffer, encode and write it to the |
||||
* output file. |
||||
*/ |
||||
static int load_encode_and_write(AVAudioFifo *fifo, |
||||
AVFormatContext *output_format_context, |
||||
AVCodecContext *output_codec_context) |
||||
{ |
||||
/** Temporary storage of the output samples of the frame written to the file. */ |
||||
AVFrame *output_frame; |
||||
/**
|
||||
* Use the maximum number of possible samples per frame. |
||||
* If there is less than the maximum possible frame size in the FIFO |
||||
* buffer use this number. Otherwise, use the maximum possible frame size |
||||
*/ |
||||
const int frame_size = FFMIN(av_audio_fifo_size(fifo), |
||||
output_codec_context->frame_size); |
||||
int data_written; |
||||
|
||||
/** Initialize temporary storage for one output frame. */ |
||||
if (init_output_frame(&output_frame, output_codec_context, frame_size)) |
||||
return AVERROR_EXIT; |
||||
|
||||
/**
|
||||
* Read as many samples from the FIFO buffer as required to fill the frame. |
||||
* The samples are stored in the frame temporarily. |
||||
*/ |
||||
if (av_audio_fifo_read(fifo, (void **)output_frame->data, frame_size) < frame_size) { |
||||
fprintf(stderr, "Could not read data from FIFO\n"); |
||||
av_frame_free(&output_frame); |
||||
return AVERROR_EXIT; |
||||
} |
||||
|
||||
/** Encode one frame worth of audio samples. */ |
||||
if (encode_audio_frame(output_frame, output_format_context, |
||||
output_codec_context, &data_written)) { |
||||
av_frame_free(&output_frame); |
||||
return AVERROR_EXIT; |
||||
} |
||||
av_frame_free(&output_frame); |
||||
return 0; |
||||
} |
||||
|
||||
/** Write the trailer of the output file container. */ |
||||
static int write_output_file_trailer(AVFormatContext *output_format_context) |
||||
{ |
||||
int error; |
||||
if ((error = av_write_trailer(output_format_context)) < 0) { |
||||
fprintf(stderr, "Could not write output file trailer (error '%s')\n", |
||||
get_error_text(error)); |
||||
return error; |
||||
} |
||||
return 0; |
||||
} |
||||
|
||||
/** Convert an audio file to an AAC file in an MP4 container. */ |
||||
int main(int argc, char **argv) |
||||
{ |
||||
AVFormatContext *input_format_context = NULL, *output_format_context = NULL; |
||||
AVCodecContext *input_codec_context = NULL, *output_codec_context = NULL; |
||||
AVAudioResampleContext *resample_context = NULL; |
||||
AVAudioFifo *fifo = NULL; |
||||
int ret = AVERROR_EXIT; |
||||
|
||||
if (argc < 3) { |
||||
fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]); |
||||
exit(1); |
||||
} |
||||
|
||||
/** Register all codecs and formats so that they can be used. */ |
||||
av_register_all(); |
||||
/** Open the input file for reading. */ |
||||
if (open_input_file(argv[1], &input_format_context, |
||||
&input_codec_context)) |
||||
goto cleanup; |
||||
/** Open the output file for writing. */ |
||||
if (open_output_file(argv[2], input_codec_context, |
||||
&output_format_context, &output_codec_context)) |
||||
goto cleanup; |
||||
/** Initialize the resampler to be able to convert audio sample formats. */ |
||||
if (init_resampler(input_codec_context, output_codec_context, |
||||
&resample_context)) |
||||
goto cleanup; |
||||
/** Initialize the FIFO buffer to store audio samples to be encoded. */ |
||||
if (init_fifo(&fifo)) |
||||
goto cleanup; |
||||
/** Write the header of the output file container. */ |
||||
if (write_output_file_header(output_format_context)) |
||||
goto cleanup; |
||||
|
||||
/**
|
||||
* Loop as long as we have input samples to read or output samples |
||||
* to write; abort as soon as we have neither. |
||||
*/ |
||||
while (1) { |
||||
/** Use the encoder's desired frame size for processing. */ |
||||
const int output_frame_size = output_codec_context->frame_size; |
||||
int finished = 0; |
||||
|
||||
/**
|
||||
* Make sure that there is one frame worth of samples in the FIFO |
||||
* buffer so that the encoder can do its work. |
||||
* Since the decoder's and the encoder's frame size may differ, we |
||||
* need to FIFO buffer to store as many frames worth of input samples |
||||
* that they make up at least one frame worth of output samples. |
||||
*/ |
||||
while (av_audio_fifo_size(fifo) < output_frame_size) { |
||||
/**
|
||||
* Decode one frame worth of audio samples, convert it to the |
||||
* output sample format and put it into the FIFO buffer. |
||||
*/ |
||||
if (read_decode_convert_and_store(fifo, input_format_context, |
||||
input_codec_context, |
||||
output_codec_context, |
||||
resample_context, &finished)) |
||||
goto cleanup; |
||||
|
||||
/**
|
||||
* If we are at the end of the input file, we continue |
||||
* encoding the remaining audio samples to the output file. |
||||
*/ |
||||
if (finished) |
||||
break; |
||||
} |
||||
|
||||
/**
|
||||
* If we have enough samples for the encoder, we encode them. |
||||
* At the end of the file, we pass the remaining samples to |
||||
* the encoder. |
||||
*/ |
||||
while (av_audio_fifo_size(fifo) >= output_frame_size || |
||||
(finished && av_audio_fifo_size(fifo) > 0)) |
||||
/**
|
||||
* Take one frame worth of audio samples from the FIFO buffer, |
||||
* encode it and write it to the output file. |
||||
*/ |
||||
if (load_encode_and_write(fifo, output_format_context, |
||||
output_codec_context)) |
||||
goto cleanup; |
||||
|
||||
/**
|
||||
* If we are at the end of the input file and have encoded |
||||
* all remaining samples, we can exit this loop and finish. |
||||
*/ |
||||
if (finished) { |
||||
int data_written; |
||||
/** Flush the encoder as it may have delayed frames. */ |
||||
do { |
||||
if (encode_audio_frame(NULL, output_format_context, |
||||
output_codec_context, &data_written)) |
||||
goto cleanup; |
||||
} while (data_written); |
||||
break; |
||||
} |
||||
} |
||||
|
||||
/** Write the trailer of the output file container. */ |
||||
if (write_output_file_trailer(output_format_context)) |
||||
goto cleanup; |
||||
ret = 0; |
||||
|
||||
cleanup: |
||||
if (fifo) |
||||
av_audio_fifo_free(fifo); |
||||
if (resample_context) { |
||||
avresample_close(resample_context); |
||||
avresample_free(&resample_context); |
||||
} |
||||
if (output_codec_context) |
||||
avcodec_close(output_codec_context); |
||||
if (output_format_context) { |
||||
avio_close(output_format_context->pb); |
||||
avformat_free_context(output_format_context); |
||||
} |
||||
if (input_codec_context) |
||||
avcodec_close(input_codec_context); |
||||
if (input_format_context) |
||||
avformat_close_input(&input_format_context); |
||||
|
||||
return ret; |
||||
} |
Loading…
Reference in new issue