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Carte de Schillerkiez
13 mai 2011, par
Mis à jour : Septembre 2011
Langue : English
Type : Texte
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ffmpeg C api cutting a video when packet dts is greater than pts
10 mars 2017, par TastyCatFoodCorrupted videos
In trying to cut out a duration of one of videos using ffmpeg C api, using the code posted here : How to cut video with FFmpeg C API , ffmpeg spit out the log below :
D/logger: Loop count:9 out: pts:0 pts_time:0 dts:2002 dts_time:0.0333667 duration:2002 duration_time:0.0333667 stream_index:1
D/trim_video: Error muxing packet Invalid argumentffmpeg considercs an instruction to decompress a frame after presenting it to be a nonsense, which is well...reasonable but stringent.
My VLC player finds the video alright and plays it of course.
Note :
The code immediately below is in c++ written to be compiled with g++ as I’m developing for android. For C code, scroll down further.
My solution(g++) :
extern "C" {
#include "libavformat/avformat.h"
#include "libavutil/mathematics.h"
#include "libavutil/timestamp.h"
static void log_packet(
const AVFormatContext *fmt_ctx,
const AVPacket *pkt, const char *tag,
long count=0)
{
printf("loop count %d pts:%f dts:%f duration:%f stream_index:%d\n",
count,
static_cast<double>(pkt->pts),
static_cast<double>(pkt->dts),
static_cast<double>(pkt->duration),
pkt->stream_index);
return;
}
int trimVideo(
const char* in_filename,
const char* out_filename,
double cutFrom,
double cutUpTo)
{
AVOutputFormat *ofmt = NULL;
AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
AVPacket pkt;
int ret, i;
//jboolean copy = true;
//const char *in_filename = env->GetStringUTFChars(jstring_in_filename,&copy);
//const char *out_filename = env->GetStringUTFChars(jstring_out_filename,&copy);
long loopCount = 0;
av_register_all();
// Cutting may change the pts and dts of the resulting video;
// if frames in head position are removed.
// In the case like that, src stream's copy start pts
// need to be recorded and is used to compute the new pts value.
// e.g.
// new_pts = current_pts - trim_start_position_pts;
// nb-streams is the number of elements in AVFormatContext.streams.
// Initial pts value must be recorded for each stream.
//May be malloc and memset should be replaced with [].
int64_t *dts_start_from = NULL;
int64_t *pts_start_from = NULL;
if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {
printf( "Could not open input file '%s'", in_filename);
goto end;
}
if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {
printf("Failed to retrieve input stream information");
goto end;
}
av_dump_format(ifmt_ctx, 0, in_filename, 0);
avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename);
if (!ofmt_ctx) {
printf( "Could not create output context\n");
ret = AVERROR_UNKNOWN;
goto end;
}
ofmt = ofmt_ctx->oformat;
//preparing streams
for (i = 0; i < ifmt_ctx->nb_streams; i++) {
AVStream *in_stream = ifmt_ctx->streams[i];
AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec);
if (!out_stream) {
printf( "Failed allocating output stream\n");
ret = AVERROR_UNKNOWN;
goto end;
}
ret = avcodec_copy_context(out_stream->codec, in_stream->codec);
if (ret < 0) {
printf( "Failed to copy context from input to output stream codec context\n");
goto end;
}
out_stream->codec->codec_tag = 0;
if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
out_stream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
}
av_dump_format(ofmt_ctx, 0, out_filename, 1);
if (!(ofmt->flags & AVFMT_NOFILE)) {
ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);
if (ret < 0) {
printf( "Could not open output file '%s'", out_filename);
goto end;
}
}
//preparing the header
ret = avformat_write_header(ofmt_ctx, NULL);
if (ret < 0) {
printf( "Error occurred when opening output file\n");
goto end;
}
// av_seek_frame translates AV_TIME_BASE into an appropriate time base.
ret = av_seek_frame(ifmt_ctx, -1, cutFrom*AV_TIME_BASE, AVSEEK_FLAG_ANY);
if (ret < 0) {
printf( "Error seek\n");
goto end;
}
dts_start_from = static_cast(
malloc(sizeof(int64_t) * ifmt_ctx->nb_streams));
memset(dts_start_from, 0, sizeof(int64_t) * ifmt_ctx->nb_streams);
pts_start_from = static_cast(
malloc(sizeof(int64_t) * ifmt_ctx->nb_streams));
memset(pts_start_from, 0, sizeof(int64_t) * ifmt_ctx->nb_streams);
//writing
while (1) {
AVStream *in_stream, *out_stream;
//reading frame into pkt
ret = av_read_frame(ifmt_ctx, &pkt);
if (ret < 0)
break;
in_stream = ifmt_ctx->streams[pkt.stream_index];
out_stream = ofmt_ctx->streams[pkt.stream_index];
//if end reached
if (av_q2d(in_stream->time_base) * pkt.pts > cutUpTo) {
av_packet_unref(&pkt);
break;
}
// Recording the initial pts value for each stream
// Recording dts does not do the trick because AVPacket.dts values
// in some video files are larger than corresponding pts values
// and ffmpeg does not like it.
if (dts_start_from[pkt.stream_index] == 0) {
dts_start_from[pkt.stream_index] = pkt.pts;
printf("dts_initial_value: %f for stream index: %d \n",
static_cast<double>(dts_start_from[pkt.stream_index]),
pkt.stream_index
);
}
if (pts_start_from[pkt.stream_index] == 0) {
pts_start_from[pkt.stream_index] = pkt.pts;
printf( "pts_initial_value: %f for stream index %d\n",
static_cast<double>(pts_start_from[pkt.stream_index]),
pkt.stream_index);
}
log_packet(ifmt_ctx, &pkt, "in",loopCount);
/* Computes pts etc
* av_rescale_q_rend etc are countering changes in time_base between
* out_stream and in_stream, so regardless of time_base values for
* in and out streams, the rate at which frames are refreshed remains
* the same.
*
pkt.pts = pkt.pts * (in_stream->time_base/ out_stream->time_base)
As `time_base == 1/frame_rate`, the above is an equivalent of
(out_stream_frame_rate/in_stream_frame_rate)*pkt.pts where
frame_rate is the number of frames to be displayed per second.
AV_ROUND_PASS_MINMAX may set pts or dts to AV_NOPTS_VALUE
* */
pkt.pts =
av_rescale_q_rnd(
pkt.pts - pts_start_from[pkt.stream_index],
static_cast<avrational>(in_stream->time_base),
static_cast<avrational>(out_stream->time_base),
static_cast<avrounding>(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
pkt.dts =
av_rescale_q_rnd(
pkt.dts - dts_start_from[pkt.stream_index],
static_cast<avrational>(in_stream->time_base),
static_cast<avrational>(out_stream->time_base),
static_cast<avrounding>(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
if(pkt.dts>pkt.pts) pkt.dts = pkt.pts -1;
if(pkt.dts < 0) pkt.dts = 0;
if(pkt.pts < 0) pkt.pts = 0;
pkt.duration = av_rescale_q(
pkt.duration,
in_stream->time_base,
out_stream->time_base);
pkt.pos = -1;
log_packet(ofmt_ctx, &pkt, "out",loopCount);
// Writes to the file after buffering packets enough to generate a frame
// and probably sorting packets in dts order.
ret = av_interleaved_write_frame(ofmt_ctx, &pkt);
// ret = av_write_frame(ofmt_ctx, &pkt);
if (ret < 0) {
printf( "Error muxing packet %d \n", ret);
//continue;
break;
}
av_packet_unref(&pkt);
++loopCount;
}
//Writing end code?
av_write_trailer(ofmt_ctx);
end:
avformat_close_input(&ifmt_ctx);
if(dts_start_from)free(dts_start_from);
if(pts_start_from)free(pts_start_from);
/* close output */
if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
avio_closep(&ofmt_ctx->pb);
avformat_free_context(ofmt_ctx);
if (ret < 0 && ret != AVERROR_EOF) {
//printf( "Error occurred: %s\n", av_err2str(ret));
return 1;
}
return 0;
}
}
</avrounding></avrational></avrational></avrounding></avrational></avrational></double></double></double></double></double>c compatible(Console says g++ but I’m sure this is C code)
#include "libavformat/avformat.h"
#include "libavutil/mathematics.h"
#include "libavutil/timestamp.h"
static void log_packet(
const AVFormatContext *fmt_ctx,
const AVPacket *pkt, const char *tag,
long count)
{
printf("loop count %d pts:%f dts:%f duration:%f stream_index:%d\n",
count,
(double)pkt->pts,
(double)pkt->dts,
(double)pkt->duration,
pkt->stream_index);
return;
}
int trimVideo(
const char* in_filename,
const char* out_filename,
double cutFrom,
double cutUpTo)
{
AVOutputFormat *ofmt = NULL;
AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
AVPacket pkt;
int ret, i;
//jboolean copy = true;
//const char *in_filename = env->GetStringUTFChars(jstring_in_filename,&copy);
//const char *out_filename = env->GetStringUTFChars(jstring_out_filename,&copy);
long loopCount = 0;
av_register_all();
// Cutting may change the pts and dts of the resulting video;
// if frames in head position are removed.
// In the case like that, src stream's copy start pts
// need to be recorded and is used to compute the new pts value.
// e.g.
// new_pts = current_pts - trim_start_position_pts;
// nb-streams is the number of elements in AVFormatContext.streams.
// Initial pts value must be recorded for each stream.
//May be malloc and memset should be replaced with [].
int64_t *dts_start_from = NULL;
int64_t *pts_start_from = NULL;
if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {
printf( "Could not open input file '%s'", in_filename);
goto end;
}
if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {
printf("Failed to retrieve input stream information");
goto end;
}
av_dump_format(ifmt_ctx, 0, in_filename, 0);
avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename);
if (!ofmt_ctx) {
printf( "Could not create output context\n");
ret = AVERROR_UNKNOWN;
goto end;
}
ofmt = ofmt_ctx->oformat;
//preparing streams
for (i = 0; i < ifmt_ctx->nb_streams; i++) {
AVStream *in_stream = ifmt_ctx->streams[i];
AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec);
if (!out_stream) {
printf( "Failed allocating output stream\n");
ret = AVERROR_UNKNOWN;
goto end;
}
ret = avcodec_copy_context(out_stream->codec, in_stream->codec);
if (ret < 0) {
printf( "Failed to copy context from input to output stream codec context\n");
goto end;
}
out_stream->codec->codec_tag = 0;
if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
out_stream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
}
av_dump_format(ofmt_ctx, 0, out_filename, 1);
if (!(ofmt->flags & AVFMT_NOFILE)) {
ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);
if (ret < 0) {
printf( "Could not open output file '%s'", out_filename);
goto end;
}
}
//preparing the header
ret = avformat_write_header(ofmt_ctx, NULL);
if (ret < 0) {
printf( "Error occurred when opening output file\n");
goto end;
}
// av_seek_frame translates AV_TIME_BASE into an appropriate time base.
ret = av_seek_frame(ifmt_ctx, -1, cutFrom*AV_TIME_BASE, AVSEEK_FLAG_ANY);
if (ret < 0) {
printf( "Error seek\n");
goto end;
}
dts_start_from = (int64_t*)
malloc(sizeof(int64_t) * ifmt_ctx->nb_streams);
memset(dts_start_from, 0, sizeof(int64_t) * ifmt_ctx->nb_streams);
pts_start_from = (int64_t*)
malloc(sizeof(int64_t) * ifmt_ctx->nb_streams);
memset(pts_start_from, 0, sizeof(int64_t) * ifmt_ctx->nb_streams);
//writing
while (1) {
AVStream *in_stream, *out_stream;
//reading frame into pkt
ret = av_read_frame(ifmt_ctx, &pkt);
if (ret < 0)
break;
in_stream = ifmt_ctx->streams[pkt.stream_index];
out_stream = ofmt_ctx->streams[pkt.stream_index];
//if end reached
if (av_q2d(in_stream->time_base) * pkt.pts > cutUpTo) {
av_packet_unref(&pkt);
break;
}
// Recording the initial pts value for each stream
// Recording dts does not do the trick because AVPacket.dts values
// in some video files are larger than corresponding pts values
// and ffmpeg does not like it.
if (dts_start_from[pkt.stream_index] == 0) {
dts_start_from[pkt.stream_index] = pkt.pts;
printf("dts_initial_value: %f for stream index: %d \n",
(double)dts_start_from[pkt.stream_index],
pkt.stream_index
);
}
if (pts_start_from[pkt.stream_index] == 0) {
pts_start_from[pkt.stream_index] = pkt.pts;
printf( "pts_initial_value: %f for stream index %d\n",
(double)pts_start_from[pkt.stream_index],
pkt.stream_index);
}
log_packet(ifmt_ctx, &pkt, "in",loopCount);
/* Computes pts etc
* av_rescale_q_rend etc are countering changes in time_base between
* out_stream and in_stream, so regardless of time_base values for
* in and out streams, the rate at which frames are refreshed remains
* the same.
*
pkt.pts = pkt.pts * (in_stream->time_base/ out_stream->time_base)
As `time_base == 1/frame_rate`, the above is an equivalent of
(out_stream_frame_rate/in_stream_frame_rate)*pkt.pts where
frame_rate is the number of frames to be displayed per second.
AV_ROUND_PASS_MINMAX may set pts or dts to AV_NOPTS_VALUE
* */
pkt.pts =
av_rescale_q_rnd(
pkt.pts - pts_start_from[pkt.stream_index],
(AVRational)in_stream->time_base,
(AVRational)out_stream->time_base,
(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
pkt.dts =
av_rescale_q_rnd(
pkt.dts - dts_start_from[pkt.stream_index],
(AVRational)in_stream->time_base,
(AVRational)out_stream->time_base,
AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);
if(pkt.dts>pkt.pts) pkt.dts = pkt.pts -1;
if(pkt.dts < 0) pkt.dts = 0;
if(pkt.pts < 0) pkt.pts = 0;
pkt.duration = av_rescale_q(
pkt.duration,
in_stream->time_base,
out_stream->time_base);
pkt.pos = -1;
log_packet(ofmt_ctx, &pkt, "out",loopCount);
// Writes to the file after buffering packets enough to generate a frame
// and probably sorting packets in dts order.
ret = av_interleaved_write_frame(ofmt_ctx, &pkt);
// ret = av_write_frame(ofmt_ctx, &pkt);
if (ret < 0) {
printf( "Error muxing packet %d \n", ret);
//continue;
break;
}
av_packet_unref(&pkt);
++loopCount;
}
//Writing end code?
av_write_trailer(ofmt_ctx);
end:
avformat_close_input(&ifmt_ctx);
if(dts_start_from)free(dts_start_from);
if(pts_start_from)free(pts_start_from);
/* close output */
if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
avio_closep(&ofmt_ctx->pb);
avformat_free_context(ofmt_ctx);
if (ret < 0 && ret != AVERROR_EOF) {
//printf( "Error occurred: %s\n", av_err2str(ret));
return 1;
}
return 0;
}What is the problem
My code does not produce the error because I’m doing
new_dts = current_dts - initial_pts_for_current_stream. It works but now dts values are not properly computed.How to recalculate dts properly ?
P.S
Since Olaf seems to have a very strong opinion, posting the build console message for my main.c.
I don’t really know C or C++ but GNU gcc seems to be calling gcc for compiling and g++ for linking.
Well, the extension for my main is now .c and the compiler being called is gcc, so that should at least mean I have got a code written in C language...------------- Build: Debug in videoTrimmer (compiler: GNU GCC Compiler)---------------
gcc -Wall -fexceptions -std=c99 -g -I/home/d/Android/Sdk/ndk-bundle/sources/FFmpeg/local/include -I/usr/include -I/usr/local/include -c /home/d/CodeBlockWorkplace/videoTrimmer/main.c -o obj/Debug/main.o
/home/d/CodeBlockWorkplace/videoTrimmer/main.c: In function ‘log_packet’:
/home/d/CodeBlockWorkplace/videoTrimmer/main.c:15:12: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘long int’ [-Wformat=]
printf("loop count %d pts:%f dts:%f duration:%f stream_index:%d\n",
^
/home/d/CodeBlockWorkplace/videoTrimmer/main.c: In function ‘trimVideo’:
/home/d/CodeBlockWorkplace/videoTrimmer/main.c:79:9: warning: ‘codec’ is deprecated [-Wdeprecated-declarations]
AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec);
^
In file included from /home/d/CodeBlockWorkplace/videoTrimmer/main.c:3:0:
/home/d/Android/Sdk/ndk-bundle/sources/FFmpeg/local/include/libavformat/avformat.h:893:21: note: declared here
AVCodecContext *codec;
^
/home/d/CodeBlockWorkplace/videoTrimmer/main.c:86:9: warning: ‘avcodec_copy_context’ is deprecated [-Wdeprecated-declarations]
ret = avcodec_copy_context(out_stream->codec, in_stream->codec);
^
In file included from /home/d/Android/Sdk/ndk-bundle/sources/FFmpeg/local/include/libavformat/avformat.h:319:0,
from /home/d/CodeBlockWorkplace/videoTrimmer/main.c:3:
/home/d/Android/Sdk/ndk-bundle/sources/FFmpeg/local/include/libavcodec/avcodec.h:4286:5: note: declared here
int avcodec_copy_context(AVCodecContext *dest, const AVCodecContext *src);
^
/home/d/CodeBlockWorkplace/videoTrimmer/main.c:86:9: warning: ‘codec’ is deprecated [-Wdeprecated-declarations]
ret = avcodec_copy_context(out_stream->codec, in_stream->codec);
^
In file included from /home/d/CodeBlockWorkplace/videoTrimmer/main.c:3:0:
/home/d/Android/Sdk/ndk-bundle/sources/FFmpeg/local/include/libavformat/avformat.h:893:21: note: declared here
AVCodecContext *codec;
^
/home/d/CodeBlockWorkplace/videoTrimmer/main.c:86:9: warning: ‘codec’ is deprecated [-Wdeprecated-declarations]
ret = avcodec_copy_context(out_stream->codec, in_stream->codec);
^
In file included from /home/d/CodeBlockWorkplace/videoTrimmer/main.c:3:0:
/home/d/Android/Sdk/ndk-bundle/sources/FFmpeg/local/include/libavformat/avformat.h:893:21: note: declared here
AVCodecContext *codec;
^
/home/d/CodeBlockWorkplace/videoTrimmer/main.c:91:9: warning: ‘codec’ is deprecated [-Wdeprecated-declarations]
out_stream->codec->codec_tag = 0;
^
In file included from /home/d/CodeBlockWorkplace/videoTrimmer/main.c:3:0:
/home/d/Android/Sdk/ndk-bundle/sources/FFmpeg/local/include/libavformat/avformat.h:893:21: note: declared here
AVCodecContext *codec;
^
/home/d/CodeBlockWorkplace/videoTrimmer/main.c:93:13: warning: ‘codec’ is deprecated [-Wdeprecated-declarations]
out_stream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
^
In file included from /home/d/CodeBlockWorkplace/videoTrimmer/main.c:3:0:
/home/d/Android/Sdk/ndk-bundle/sources/FFmpeg/local/include/libavformat/avformat.h:893:21: note: declared here
AVCodecContext *codec;
^
g++ -L/home/d/Android/Sdk/ndk-bundle/sources/FFmpeg/local/lib -L/usr/lib -L/usr/local/lib -o bin/Debug/videoTrimmer obj/Debug/main.o ../../Android/Sdk/ndk-bundle/sources/FFmpeg/local/lib/libavformat.a ../../Android/Sdk/ndk-bundle/sources/FFmpeg/local/lib/libavcodec.a ../../Android/Sdk/ndk-bundle/sources/FFmpeg/local/lib/libavutil.a ../../Android/Sdk/ndk-bundle/sources/FFmpeg/local/lib/libswresample.a ../../Android/Sdk/ndk-bundle/sources/FFmpeg/local/lib/libswscale.a ../../Android/Sdk/ndk-bundle/sources/FFmpeg/local/lib/libavfilter.a ../../Android/Sdk/ndk-bundle/sources/FFmpeg/local/lib/libpostproc.a ../../Android/Sdk/ndk-bundle/sources/FFmpeg/local/lib/libavdevice.a -lX11 -lvdpau -lva -lva-drm -lva-x11 -ldl -lpthread -lz -llzma -lx264
Output file is bin/Debug/videoTrimmer with size 77.24 MB
Process terminated with status 0 (0 minute(s), 16 second(s))
0 error(s), 8 warning(s) (0 minute(s), 16 second(s))
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