mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
201 lines
6.4 KiB
201 lines
6.4 KiB
/* |
|
* Bitstream filter for unpacking DivX-style packed B-frames in MPEG-4 (divx_packed) |
|
* Copyright (c) 2015 Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com> |
|
* |
|
* This file is part of FFmpeg. |
|
* |
|
* FFmpeg is free software; you can redistribute it and/or |
|
* modify it under the terms of the GNU Lesser General Public |
|
* License as published by the Free Software Foundation; either |
|
* version 2.1 of the License, or (at your option) any later version. |
|
* |
|
* FFmpeg is distributed in the hope that it will be useful, |
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of |
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
|
* Lesser General Public License for more details. |
|
* |
|
* You should have received a copy of the GNU Lesser General Public |
|
* License along with FFmpeg; if not, write to the Free Software |
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
|
*/ |
|
|
|
#include "avcodec.h" |
|
#include "bsf.h" |
|
#include "mpeg4video.h" |
|
|
|
typedef struct UnpackBFramesBSFContext { |
|
uint8_t *b_frame_buf; |
|
int b_frame_buf_size; |
|
} UnpackBFramesBSFContext; |
|
|
|
/* search next start code */ |
|
static unsigned int find_startcode(const uint8_t *buf, int buf_size, int *pos) |
|
{ |
|
unsigned int startcode = 0xFF; |
|
|
|
for (; *pos < buf_size;) { |
|
startcode = ((startcode << 8) | buf[*pos]) & 0xFFFFFFFF; |
|
*pos +=1; |
|
if ((startcode & 0xFFFFFF00) != 0x100) |
|
continue; /* no startcode */ |
|
return startcode; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/* determine the position of the packed marker in the userdata, |
|
* the number of VOPs and the position of the second VOP */ |
|
static void scan_buffer(const uint8_t *buf, int buf_size, |
|
int *pos_p, int *nb_vop, int *pos_vop2) { |
|
unsigned int startcode; |
|
int pos, i; |
|
|
|
for (pos = 0; pos < buf_size;) { |
|
startcode = find_startcode(buf, buf_size, &pos); |
|
|
|
if (startcode == USER_DATA_STARTCODE && pos_p) { |
|
/* check if the (DivX) userdata string ends with 'p' (packed) */ |
|
for (i = 0; i < 255 && pos + i + 1 < buf_size; i++) { |
|
if (buf[pos + i] == 'p' && buf[pos + i + 1] == '\0') { |
|
*pos_p = pos + i; |
|
break; |
|
} |
|
} |
|
} else if (startcode == VOP_STARTCODE && nb_vop) { |
|
*nb_vop += 1; |
|
if (*nb_vop == 2 && pos_vop2) { |
|
*pos_vop2 = pos - 4; /* subtract 4 bytes startcode */ |
|
} |
|
} |
|
} |
|
} |
|
|
|
/* allocate new buffer and copy size bytes from src */ |
|
static uint8_t *create_new_buffer(const uint8_t *src, int size) { |
|
uint8_t *dst = av_malloc(size + AV_INPUT_BUFFER_PADDING_SIZE); |
|
|
|
if (dst) { |
|
memcpy(dst, src, size); |
|
memset(dst + size, 0, AV_INPUT_BUFFER_PADDING_SIZE); |
|
} |
|
|
|
return dst; |
|
} |
|
|
|
static int mpeg4_unpack_bframes_filter(AVBSFContext *ctx, AVPacket *out) |
|
{ |
|
UnpackBFramesBSFContext *s = ctx->priv_data; |
|
int pos_p = -1, nb_vop = 0, pos_vop2 = -1, ret = 0; |
|
AVPacket *in; |
|
|
|
ret = ff_bsf_get_packet(ctx, &in); |
|
if (ret < 0) |
|
return ret; |
|
|
|
scan_buffer(in->data, in->size, &pos_p, &nb_vop, &pos_vop2); |
|
av_log(ctx, AV_LOG_DEBUG, "Found %d VOP startcode(s) in this packet.\n", nb_vop); |
|
|
|
if (pos_vop2 >= 0) { |
|
if (s->b_frame_buf) { |
|
av_log(ctx, AV_LOG_WARNING, |
|
"Missing one N-VOP packet, discarding one B-frame.\n"); |
|
av_freep(&s->b_frame_buf); |
|
s->b_frame_buf_size = 0; |
|
} |
|
/* store the packed B-frame in the BSFContext */ |
|
s->b_frame_buf_size = in->size - pos_vop2; |
|
s->b_frame_buf = create_new_buffer(in->data + pos_vop2, s->b_frame_buf_size); |
|
if (!s->b_frame_buf) { |
|
s->b_frame_buf_size = 0; |
|
av_packet_free(&in); |
|
return AVERROR(ENOMEM); |
|
} |
|
} |
|
|
|
if (nb_vop > 2) { |
|
av_log(ctx, AV_LOG_WARNING, |
|
"Found %d VOP headers in one packet, only unpacking one.\n", nb_vop); |
|
} |
|
|
|
if (nb_vop == 1 && s->b_frame_buf) { |
|
/* use frame from BSFContext */ |
|
ret = av_packet_copy_props(out, in); |
|
if (ret < 0) { |
|
av_packet_free(&in); |
|
return ret; |
|
} |
|
|
|
ret = av_packet_from_data(out, s->b_frame_buf, s->b_frame_buf_size); |
|
if (ret < 0) { |
|
av_packet_free(&in); |
|
return ret; |
|
} |
|
if (in->size <= MAX_NVOP_SIZE) { |
|
/* N-VOP */ |
|
av_log(ctx, AV_LOG_DEBUG, "Skipping N-VOP.\n"); |
|
s->b_frame_buf = NULL; |
|
s->b_frame_buf_size = 0; |
|
} else { |
|
/* copy packet into BSFContext */ |
|
s->b_frame_buf_size = in->size; |
|
s->b_frame_buf = create_new_buffer(in->data, in->size); |
|
if (!s->b_frame_buf) { |
|
s->b_frame_buf_size = 0; |
|
av_packet_unref(out); |
|
av_packet_free(&in); |
|
return AVERROR(ENOMEM); |
|
} |
|
} |
|
} else if (nb_vop >= 2) { |
|
/* use first frame of the packet */ |
|
av_packet_move_ref(out, in); |
|
out->size = pos_vop2; |
|
} else if (pos_p >= 0) { |
|
av_log(ctx, AV_LOG_DEBUG, "Updating DivX userdata (remove trailing 'p').\n"); |
|
av_packet_move_ref(out, in); |
|
/* remove 'p' (packed) from the end of the (DivX) userdata string */ |
|
out->data[pos_p] = '\0'; |
|
} else { |
|
/* copy packet */ |
|
av_packet_move_ref(out, in); |
|
} |
|
|
|
av_packet_free(&in); |
|
|
|
return 0; |
|
} |
|
|
|
static int mpeg4_unpack_bframes_init(AVBSFContext *ctx) |
|
{ |
|
if (ctx->par_in->extradata) { |
|
int pos_p_ext = -1; |
|
scan_buffer(ctx->par_in->extradata, ctx->par_in->extradata_size, &pos_p_ext, NULL, NULL); |
|
if (pos_p_ext >= 0) { |
|
av_log(ctx, AV_LOG_DEBUG, |
|
"Updating DivX userdata (remove trailing 'p') in extradata.\n"); |
|
ctx->par_out->extradata[pos_p_ext] = '\0'; |
|
} |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static void mpeg4_unpack_bframes_close(AVBSFContext *bsfc) |
|
{ |
|
UnpackBFramesBSFContext *ctx = bsfc->priv_data; |
|
av_freep(&ctx->b_frame_buf); |
|
} |
|
|
|
static const enum AVCodecID codec_ids[] = { |
|
AV_CODEC_ID_MPEG4, AV_CODEC_ID_NONE, |
|
}; |
|
|
|
const AVBitStreamFilter ff_mpeg4_unpack_bframes_bsf = { |
|
.name = "mpeg4_unpack_bframes", |
|
.priv_data_size = sizeof(UnpackBFramesBSFContext), |
|
.init = mpeg4_unpack_bframes_init, |
|
.filter = mpeg4_unpack_bframes_filter, |
|
.close = mpeg4_unpack_bframes_close, |
|
.codec_ids = codec_ids, |
|
};
|
|
|