mirror of https://github.com/FFmpeg/FFmpeg.git
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/*
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* Media 100 decoder |
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* Copyright (c) 2022 Paul B Mahol |
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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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* @file |
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* Media 100 decoder. |
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*/ |
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#include <inttypes.h> |
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#include "libavutil/intreadwrite.h" |
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#include "avcodec.h" |
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#include "bytestream.h" |
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#include "codec_internal.h" |
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typedef struct Media100Context { |
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AVCodecContext *avctx; // wrapper context for mjpegb
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AVPacket *pkt; |
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} Media100Context; |
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static av_cold int media100_decode_init(AVCodecContext *avctx) |
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{ |
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Media100Context *ctx = avctx->priv_data; |
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const AVCodec *codec; |
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int ret; |
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codec = avcodec_find_decoder(AV_CODEC_ID_MJPEGB); |
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if (!codec) |
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return AVERROR_BUG; |
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ctx->avctx = avcodec_alloc_context3(codec); |
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if (!ctx->avctx) |
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return AVERROR(ENOMEM); |
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ctx->avctx->thread_count = 1; |
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ctx->avctx->flags = avctx->flags; |
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ctx->avctx->flags2 = avctx->flags2; |
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ctx->avctx->width = ctx->avctx->coded_width = avctx->width; |
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ctx->avctx->height = ctx->avctx->coded_height = avctx->height; |
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ret = avcodec_open2(ctx->avctx, codec, NULL); |
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if (ret < 0) |
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return ret; |
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ctx->pkt = av_packet_alloc(); |
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if (!ctx->pkt) |
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return AVERROR(ENOMEM); |
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return 0; |
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} |
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static int media100_decode_frame(AVCodecContext *avctx, |
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AVFrame *frame, int *got_frame, |
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AVPacket *avpkt) |
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{ |
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Media100Context *ctx = avctx->priv_data; |
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unsigned second_field_offset = 0; |
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unsigned next_field = 0; |
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unsigned dht_offset[2]; |
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unsigned dqt_offset[2]; |
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unsigned sod_offset[2]; |
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unsigned sof_offset[2]; |
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unsigned sos_offset[2]; |
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unsigned field = 0; |
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GetByteContext gb; |
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PutByteContext pb; |
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AVPacket *pkt; |
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int ret; |
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if (avpkt->size + 1024 > ctx->pkt->size) { |
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ret = av_grow_packet(ctx->pkt, avpkt->size + 1024 - ctx->pkt->size); |
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if (ret < 0) |
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return ret; |
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} |
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ret = av_packet_make_writable(ctx->pkt); |
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if (ret < 0) |
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return ret; |
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bytestream2_init(&gb, avpkt->data, avpkt->size); |
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bytestream2_init_writer(&pb, ctx->pkt->data, ctx->pkt->size); |
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second_field: |
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bytestream2_put_be32(&pb, 0); |
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bytestream2_put_be32(&pb, AV_RB32("mjpg")); |
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bytestream2_put_be32(&pb, 0); |
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bytestream2_put_be32(&pb, 0); |
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for (int i = 0; i < 6; i++) |
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bytestream2_put_be32(&pb, 0); |
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sof_offset[field] = bytestream2_tell_p(&pb); |
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bytestream2_put_be16(&pb, 17); |
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bytestream2_put_byte(&pb, 8); |
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bytestream2_put_be16(&pb, avctx->height / 2); |
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bytestream2_put_be16(&pb, avctx->width); |
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bytestream2_put_byte(&pb, 3); |
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bytestream2_put_byte(&pb, 1); |
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bytestream2_put_byte(&pb, 0x21); |
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bytestream2_put_byte(&pb, 0); |
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bytestream2_put_byte(&pb, 2); |
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bytestream2_put_byte(&pb, 0x11); |
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bytestream2_put_byte(&pb, 1); |
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bytestream2_put_byte(&pb, 3); |
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bytestream2_put_byte(&pb, 0x11); |
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bytestream2_put_byte(&pb, 1); |
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sos_offset[field] = bytestream2_tell_p(&pb); |
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bytestream2_put_be16(&pb, 12); |
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bytestream2_put_byte(&pb, 3); |
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bytestream2_put_byte(&pb, 1); |
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bytestream2_put_byte(&pb, 0); |
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bytestream2_put_byte(&pb, 2); |
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bytestream2_put_byte(&pb, 0x11); |
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bytestream2_put_byte(&pb, 3); |
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bytestream2_put_byte(&pb, 0x11); |
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bytestream2_put_byte(&pb, 0); |
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bytestream2_put_byte(&pb, 0); |
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bytestream2_put_byte(&pb, 0); |
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dqt_offset[field] = bytestream2_tell_p(&pb); |
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bytestream2_put_be16(&pb, 132); |
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bytestream2_put_byte(&pb, 0); |
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bytestream2_skip(&gb, 4); |
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for (int i = 0; i < 64; i++) |
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bytestream2_put_byte(&pb, bytestream2_get_be32(&gb)); |
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bytestream2_put_byte(&pb, 1); |
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for (int i = 0; i < 64; i++) |
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bytestream2_put_byte(&pb, bytestream2_get_be32(&gb)); |
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dht_offset[field] = 0; |
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sod_offset[field] = bytestream2_tell_p(&pb); |
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for (int i = bytestream2_tell(&gb) + 8; next_field == 0 && i < avpkt->size - 4; i++) { |
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if (AV_RB32(avpkt->data + i) == 0x00000001) { |
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next_field = i; |
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break; |
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} |
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} |
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bytestream2_skip(&gb, 8); |
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bytestream2_copy_buffer(&pb, &gb, next_field - bytestream2_tell(&gb)); |
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bytestream2_put_be64(&pb, 0); |
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if (field == 0) { |
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field = 1; |
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second_field_offset = bytestream2_tell_p(&pb); |
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next_field = avpkt->size; |
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goto second_field; |
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} |
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pkt = ctx->pkt; |
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AV_WB32(pkt->data + 8, second_field_offset); |
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AV_WB32(pkt->data + 12, second_field_offset); |
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AV_WB32(pkt->data + 16, second_field_offset); |
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AV_WB32(pkt->data + 20, dqt_offset[0]); |
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AV_WB32(pkt->data + 24, dht_offset[0]); |
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AV_WB32(pkt->data + 28, sof_offset[0]); |
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AV_WB32(pkt->data + 32, sos_offset[0]); |
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AV_WB32(pkt->data + 36, sod_offset[0]); |
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AV_WB32(pkt->data + second_field_offset + 8, bytestream2_tell_p(&pb) - second_field_offset); |
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AV_WB32(pkt->data + second_field_offset + 12, bytestream2_tell_p(&pb) - second_field_offset); |
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AV_WB32(pkt->data + second_field_offset + 16, 0); |
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AV_WB32(pkt->data + second_field_offset + 20, dqt_offset[1] - second_field_offset); |
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AV_WB32(pkt->data + second_field_offset + 24, dht_offset[1]); |
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AV_WB32(pkt->data + second_field_offset + 28, sof_offset[1] - second_field_offset); |
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AV_WB32(pkt->data + second_field_offset + 32, sos_offset[1] - second_field_offset); |
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AV_WB32(pkt->data + second_field_offset + 36, sod_offset[1] - second_field_offset); |
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pkt->size = bytestream2_tell_p(&pb); |
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ret = avcodec_send_packet(ctx->avctx, pkt); |
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if (ret < 0) { |
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av_log(avctx, AV_LOG_ERROR, "Error submitting a packet for decoding\n"); |
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return ret; |
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} |
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ret = avcodec_receive_frame(ctx->avctx, frame); |
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if (ret < 0) |
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return ret; |
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*got_frame = 1; |
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return avpkt->size; |
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} |
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static av_cold int media100_decode_end(AVCodecContext *avctx) |
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{ |
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Media100Context *ctx = avctx->priv_data; |
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avcodec_free_context(&ctx->avctx); |
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av_packet_free(&ctx->pkt); |
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return 0; |
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} |
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const FFCodec ff_media100_decoder = { |
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.p.name = "media100", |
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CODEC_LONG_NAME("Media 100"), |
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.p.type = AVMEDIA_TYPE_VIDEO, |
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.p.id = AV_CODEC_ID_MEDIA100, |
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.priv_data_size = sizeof(Media100Context), |
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.init = media100_decode_init, |
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.close = media100_decode_end, |
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FF_CODEC_DECODE_CB(media100_decode_frame), |
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.caps_internal = FF_CODEC_CAP_INIT_CLEANUP, |
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}; |
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