mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-02 03:06:28 +02:00
1eb6bfbc1f
instead of an ad-hoc function to search for start codes in order to remove code duplication and to improve performance. Improved performance of finding startcodes from 52606 decicycles to 9543 decicycles based upon 262144 runs for a 1 Mb/s MPEG4 video. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@googlemail.com> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
180 lines
5.6 KiB
C
180 lines
5.6 KiB
C
/*
|
|
* 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 "internal.h"
|
|
#include "mpeg4video.h"
|
|
|
|
typedef struct UnpackBFramesBSFContext {
|
|
AVPacket *b_frame;
|
|
} UnpackBFramesBSFContext;
|
|
|
|
/* 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) {
|
|
uint32_t startcode;
|
|
const uint8_t *end = buf + buf_size, *pos = buf;
|
|
|
|
while (pos < end) {
|
|
startcode = -1;
|
|
pos = avpriv_find_start_code(pos, end, &startcode);
|
|
|
|
if (startcode == USER_DATA_STARTCODE && pos_p) {
|
|
/* check if the (DivX) userdata string ends with 'p' (packed) */
|
|
for (int i = 0; i < 255 && pos + i + 1 < end; i++) {
|
|
if (pos[i] == 'p' && pos[i + 1] == '\0') {
|
|
*pos_p = pos + i - buf;
|
|
break;
|
|
}
|
|
}
|
|
} else if (startcode == VOP_STARTCODE && nb_vop) {
|
|
*nb_vop += 1;
|
|
if (*nb_vop == 2 && pos_vop2) {
|
|
*pos_vop2 = pos - buf - 4; /* subtract 4 bytes startcode */
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
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->data) {
|
|
av_log(ctx, AV_LOG_WARNING,
|
|
"Missing one N-VOP packet, discarding one B-frame.\n");
|
|
av_packet_unref(s->b_frame);
|
|
}
|
|
/* store the packed B-frame in the BSFContext */
|
|
ret = av_packet_ref(s->b_frame, in);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
s->b_frame->size -= pos_vop2;
|
|
s->b_frame->data += pos_vop2;
|
|
}
|
|
|
|
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->data) {
|
|
/* use frame from BSFContext */
|
|
av_packet_move_ref(out, s->b_frame);
|
|
|
|
/* use properties from current input packet */
|
|
ret = av_packet_copy_props(out, in);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
if (in->size <= MAX_NVOP_SIZE) {
|
|
/* N-VOP */
|
|
av_log(ctx, AV_LOG_DEBUG, "Skipping N-VOP.\n");
|
|
} else {
|
|
/* copy packet into BSFContext */
|
|
av_packet_move_ref(s->b_frame, in);
|
|
}
|
|
} 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) {
|
|
ret = av_packet_make_writable(in);
|
|
if (ret < 0)
|
|
goto fail;
|
|
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);
|
|
}
|
|
|
|
fail:
|
|
if (ret < 0)
|
|
av_packet_unref(out);
|
|
av_packet_free(&in);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int mpeg4_unpack_bframes_init(AVBSFContext *ctx)
|
|
{
|
|
UnpackBFramesBSFContext *s = ctx->priv_data;
|
|
|
|
s->b_frame = av_packet_alloc();
|
|
if (!s->b_frame)
|
|
return AVERROR(ENOMEM);
|
|
|
|
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_flush(AVBSFContext *bsfc)
|
|
{
|
|
UnpackBFramesBSFContext *ctx = bsfc->priv_data;
|
|
av_packet_unref(ctx->b_frame);
|
|
}
|
|
|
|
static void mpeg4_unpack_bframes_close(AVBSFContext *bsfc)
|
|
{
|
|
UnpackBFramesBSFContext *ctx = bsfc->priv_data;
|
|
av_packet_free(&ctx->b_frame);
|
|
}
|
|
|
|
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,
|
|
.flush = mpeg4_unpack_bframes_flush,
|
|
.close = mpeg4_unpack_bframes_close,
|
|
.codec_ids = codec_ids,
|
|
};
|