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Les formats acceptés
28 janvier 2010, parLes commandes suivantes permettent d’avoir des informations sur les formats et codecs gérés par l’installation local de ffmpeg :
ffmpeg -codecs ffmpeg -formats
Les format videos acceptés en entrée
Cette liste est non exhaustive, elle met en exergue les principaux formats utilisés : h264 : H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 m4v : raw MPEG-4 video format flv : Flash Video (FLV) / Sorenson Spark / Sorenson H.263 Theora wmv :
Les formats vidéos de sortie possibles
Dans un premier temps on (...) -
Encoding and processing into web-friendly formats
13 avril 2011, parMediaSPIP automatically converts uploaded files to internet-compatible formats.
Video files are encoded in MP4, Ogv and WebM (supported by HTML5) and MP4 (supported by Flash).
Audio files are encoded in MP3 and Ogg (supported by HTML5) and MP3 (supported by Flash).
Where possible, text is analyzed in order to retrieve the data needed for search engine detection, and then exported as a series of image files.
All uploaded files are stored online in their original format, so you can (...) -
Ajouter notes et légendes aux images
7 février 2011, parPour pouvoir ajouter notes et légendes aux images, la première étape est d’installer le plugin "Légendes".
Une fois le plugin activé, vous pouvez le configurer dans l’espace de configuration afin de modifier les droits de création / modification et de suppression des notes. Par défaut seuls les administrateurs du site peuvent ajouter des notes aux images.
Modification lors de l’ajout d’un média
Lors de l’ajout d’un média de type "image" un nouveau bouton apparait au dessus de la prévisualisation (...)
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Screen Recording with FFmpeg-Lib with c++
27 janvier 2020, par BaschdelI’m trying to record the whole desktop stream with FFmpeg on Windows.
I found a working example here. The Problem is that some og the functions depricated. So I tried to replace them with the updated ones.But there are some slight problems. The error "has triggered a breakpoint." occurse and also "not able to read the location."
The bigger problem is that I don’t know if this is the right way to do this..My code looks like this :
using namespace std;
/* initialize the resources*/
Recorder::Recorder()
{
av_register_all();
avcodec_register_all();
avdevice_register_all();
cout<<"\nall required functions are registered successfully";
}
/* uninitialize the resources */
Recorder::~Recorder()
{
avformat_close_input(&pAVFormatContext);
if( !pAVFormatContext )
{
cout<<"\nfile closed sucessfully";
}
else
{
cout<<"\nunable to close the file";
exit(1);
}
avformat_free_context(pAVFormatContext);
if( !pAVFormatContext )
{
cout<<"\navformat free successfully";
}
else
{
cout<<"\nunable to free avformat context";
exit(1);
}
}
/* establishing the connection between camera or screen through its respective folder */
int Recorder::openCamera()
{
value = 0;
options = NULL;
pAVFormatContext = NULL;
pAVFormatContext = avformat_alloc_context();//Allocate an AVFormatContext.
openScreen(pAVFormatContext);
/* set frame per second */
value = av_dict_set( &options,"framerate","30",0 );
if(value < 0)
{
cout<<"\nerror in setting dictionary value";
exit(1);
}
value = av_dict_set( &options, "preset", "medium", 0 );
if(value < 0)
{
cout<<"\nerror in setting preset values";
exit(1);
}
// value = avformat_find_stream_info(pAVFormatContext,NULL);
if(value < 0)
{
cout<<"\nunable to find the stream information";
exit(1);
}
VideoStreamIndx = -1;
/* find the first video stream index . Also there is an API available to do the below operations */
for(int i = 0; i < pAVFormatContext->nb_streams; i++ ) // find video stream posistion/index.
{
if( pAVFormatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO )
{
VideoStreamIndx = i;
break;
}
}
if( VideoStreamIndx == -1)
{
cout<<"\nunable to find the video stream index. (-1)";
exit(1);
}
// assign pAVFormatContext to VideoStreamIndx
pAVCodecContext = pAVFormatContext->streams[VideoStreamIndx]->codec;
pAVCodec = avcodec_find_decoder(pAVCodecContext->codec_id);
if( pAVCodec == NULL )
{
cout<<"\nunable to find the decoder";
exit(1);
}
value = avcodec_open2(pAVCodecContext , pAVCodec , NULL);//Initialize the AVCodecContext to use the given AVCodec.
if( value < 0 )
{
cout<<"\nunable to open the av codec";
exit(1);
}
}
/* initialize the video output file and its properties */
int Recorder::init_outputfile()
{
outAVFormatContext = NULL;
value = 0;
output_file = "output.mp4";
avformat_alloc_output_context2(&outAVFormatContext, NULL, NULL, output_file);
if (!outAVFormatContext)
{
cout<<"\nerror in allocating av format output context";
exit(1);
}
/* Returns the output format in the list of registered output formats which best matches the provided parameters, or returns NULL if there is no match. */
output_format = av_guess_format(NULL, output_file ,NULL);
if( !output_format )
{
cout<<"\nerror in guessing the video format. try with correct format";
exit(1);
}
video_st = avformat_new_stream(outAVFormatContext ,NULL);
if( !video_st )
{
cout<<"\nerror in creating a av format new stream";
exit(1);
}
if (codec_id == AV_CODEC_ID_H264)
{
av_opt_set(outAVCodecContext->priv_data, "preset", "slow", 0);
}
outAVCodec = avcodec_find_encoder(AV_CODEC_ID_MPEG4);
if (!outAVCodec)
{
cout << "\nerror in finding the av codecs. try again with correct codec";
exit(1);
}
outAVCodecContext = avcodec_alloc_context3(outAVCodec);
if( !outAVCodecContext )
{
cout<<"\nerror in allocating the codec contexts";
exit(1);
}
/* set property of the video file */
outAVCodecContext = video_st->codec;
outAVCodecContext->codec_id = AV_CODEC_ID_MPEG4;// AV_CODEC_ID_MPEG4; // AV_CODEC_ID_H264 // AV_CODEC_ID_MPEG1VIDEO
outAVCodecContext->codec_type = AVMEDIA_TYPE_VIDEO;
outAVCodecContext->pix_fmt = AV_PIX_FMT_YUV420P;
outAVCodecContext->bit_rate = 400000; // 2500000
outAVCodecContext->width = 1920;
outAVCodecContext->height = 1080;
outAVCodecContext->gop_size = 3;
outAVCodecContext->max_b_frames = 2;
outAVCodecContext->time_base.num = 1;
outAVCodecContext->time_base.den = 30; //15fps
/* Some container formats (like MP4) require global headers to be present
Mark the encoder so that it behaves accordingly. */
if ( outAVFormatContext->oformat->flags & AVFMT_GLOBALHEADER)
{
outAVCodecContext->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
}
value = avcodec_open2(outAVCodecContext, outAVCodec, NULL);
if( value < 0)
{
cout<<"\nerror in opening the avcodec";
exit(1);
}
/* create empty video file */
if ( !(outAVFormatContext->flags & AVFMT_NOFILE) )
{
if( avio_open2(&outAVFormatContext->pb , output_file , AVIO_FLAG_WRITE ,NULL, NULL) < 0 )
{
cout<<"\nerror in creating the video file";
exit(1);
}
}
if(!outAVFormatContext->nb_streams)
{
cout<<"\noutput file dose not contain any stream";
exit(1);
}
/* imp: mp4 container or some advanced container file required header information*/
value = avformat_write_header(outAVFormatContext , &options);
if(value < 0)
{
cout<<"\nerror in writing the header context";
exit(1);
}
/*
// uncomment here to view the complete video file informations
cout<<"\n\nOutput file information :\n\n";
av_dump_format(outAVFormatContext , 0 ,output_file ,1);
*/
}
int Recorder::stop() {
threading = false;
demux->join();
rescale->join();
mux->join();
return 0;
}
int Recorder::start() {
initVideoThreads();
return 0;
}
int Recorder::initVideoThreads() {
demux = new thread(&Recorder::demuxVideoStream, this, pAVCodecContext, pAVFormatContext, VideoStreamIndx);
rescale = new thread(&Recorder::rescaleVideoStream, this, pAVCodecContext, outAVCodecContext);
demux = new thread(&Recorder::encodeVideoStream, this, outAVCodecContext);
return 0;
}
void Recorder::demuxVideoStream(AVCodecContext* codecContext, AVFormatContext* formatContext, int streamIndex)
{
// init packet
AVPacket* packet = (AVPacket*)av_malloc(sizeof(AVPacket));
av_init_packet(packet);
int ctr = 0;
while (threading)
{
if (av_read_frame(formatContext, packet) < 0) {
exit(1);
}
if (packet->stream_index == streamIndex)
{
int return_value; // = 0;
ctr++;
do
{
return_value = avcodec_send_packet(codecContext, packet);
} while (return_value == AVERROR(EAGAIN) && threading);
//int i = avcodec_send_packet(codecContext, packet);
if (return_value < 0 && threading) { // call Decoder
cout << "unable to decode video";
exit(1);
}
}
}
avcodec_send_packet(codecContext, NULL); // flush decoder
// return 0;
}
void Recorder::rescaleVideoStream(AVCodecContext* inCodecContext, AVCodecContext* outCodecContext)
{
bool closing = false;
AVFrame* inFrame = av_frame_alloc();
if (!inFrame)
{
cout << "\nunable to release the avframe resources";
exit(1);
}
int nbytes = av_image_get_buffer_size(outAVCodecContext->pix_fmt, outAVCodecContext->width, outAVCodecContext->height, 32);
uint8_t* video_outbuf = (uint8_t*)av_malloc(nbytes);
if (video_outbuf == NULL)
{
cout << "\nunable to allocate memory";
exit(1);
}
AVFrame* outFrame = av_frame_alloc();//Allocate an AVFrame and set its fields to default values.
if (!outFrame)
{
cout << "\nunable to release the avframe resources for outframe";
exit(1);
}
// Setup the data pointers and linesizes based on the specified image parameters and the provided array.
int value = av_image_fill_arrays(outFrame->data, outFrame->linesize, video_outbuf, AV_PIX_FMT_YUV420P, outAVCodecContext->width, outAVCodecContext->height, 1); // returns : the size in bytes required for src
if (value < 0)
{
cout << "\nerror in filling image array";
}
int ctr = 0;
while (threading || !closing) {
int value = avcodec_receive_frame(inCodecContext, inFrame);
if (value == 0) {
ctr++;
SwsContext* swsCtx_ = sws_getContext(inCodecContext->width,
inCodecContext->height,
inCodecContext->pix_fmt,
outAVCodecContext->width,
outAVCodecContext->height,
outAVCodecContext->pix_fmt,
SWS_BICUBIC, NULL, NULL, NULL);
sws_scale(swsCtx_, inFrame->data, inFrame->linesize, 0, inCodecContext->height, outFrame->data, outFrame->linesize);
int return_value;
do
{
return_value = avcodec_send_frame(outCodecContext, outFrame);
} while (return_value == AVERROR(EAGAIN) && threading);
}
closing = (value == AVERROR_EOF);
}
avcodec_send_frame(outCodecContext, NULL);
// av_free(video_outbuf);
// return 0;
}
void Recorder::encodeVideoStream(AVCodecContext* codecContext)
{
bool closing = true;
AVPacket* packet = (AVPacket*)av_malloc(sizeof(AVPacket));
av_init_packet(packet);
int ctr = 0;
while (threading || !closing) {
packet->data = NULL; // packet data will be allocated by the encoder
packet->size = 0;
ctr++;
int value = avcodec_receive_packet(codecContext, packet);
if (value == 0) {
if (packet->pts != AV_NOPTS_VALUE)
packet->pts = av_rescale_q(packet->pts, video_st->codec->time_base, video_st->time_base);
if (packet->dts != AV_NOPTS_VALUE)
packet->dts = av_rescale_q(packet->dts, video_st->codec->time_base, video_st->time_base);
//printf("Write frame %3d (size= %2d)\n", j++, packet->size / 1000);
if (av_write_frame(outAVFormatContext, packet) != 0)
{
cout << "\nerror in writing video frame";
}
}
closing = (value == AVERROR_EOF);
}
value = av_write_trailer(outAVFormatContext);
if (value < 0)
{
cout << "\nerror in writing av trailer";
exit(1);
}
// av_free(packet);
// return 0;
}
int Recorder::openScreen(AVFormatContext* pFormatCtx) {
/*
X11 video input device.
To enable this input device during configuration you need libxcb installed on your system. It will be automatically detected during configuration.
This device allows one to capture a region of an X11 display.
refer : https://www.ffmpeg.org/ffmpeg-devices.html#x11grab
*/
/* current below is for screen recording. to connect with camera use v4l2 as a input parameter for av_find_input_format */
pAVInputFormat = av_find_input_format("gdigrab");
//value = avformat_open_input(&pAVFormatContext, ":0.0+10,250", pAVInputFormat, NULL);
value = avformat_open_input(&pAVFormatContext, "desktop", pAVInputFormat, NULL);
if (value != 0)
{
cout << "\nerror in opening input device";
exit(1);
}
return 0;
} -
MKV Video Faster Plays Faster
4 avril 2014, par AnkushI have C# program which screenshots 3 times per second & adds this to mkv ( VP8 ) video, set FPS to 3,encoded video works but plays faster, the total length of video player shows is wrong & while playing it doesn't plays smooth it jumps like from 1sec -> 3sec -> 5sec means instread of 1 -> 2 ->3..
There is something wrong with pts value,
if ( codecContext->coded_frame->pts != AV_NOPTS_VALUE )
{
packet.pts = av_rescale_q( packet.pts, codecContext->time_base, pVideoStream->time_base );
}
if ( codecContext->coded_frame->pkt_dts != AV_NOPTS_VALUE )
{
packet.dts = av_rescale_q( packet.dts, codecContext->time_base, pVideoStream->time_base );
}while debugging codecContext->time_base shows 3FPS ( num=1 den=3 ) & pVideoStream->time_base shows ( num=1 den=1000) & packet.pts & packet.dts shows 0 ( everytime )
Whats wrong ? Anyone please give me some hint atleast.
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avconv "select" filter doesn't discard first frames
1er avril 2014, par user2152106I'm trying to segment a video using avconv's "select" filter to extract only a specific range of frames from the input file. As an example, imagine I have a 60fps video file called input.mp4, with 3000 frames (i.e. 50 seconds), and I run
avconv -i input.mp4 -vf "select='lt(n,2000)'" output1.mp4
avconv -i input.mp4 -vf "select='gte(n,2000)'" output2.mp4What I expect is that output1.mp4 has the first 2000 frames of input.mp4 (and lasts 33 seconds), and output2.mp4 has the last 1000 (and lasts 17 seconds).
I count the frames by running
avconv -i video.mp4 -vcodec copy -an -f null /dev/null 2>&1 | grep 'frame='and checking the value assigned to 'frame'.
What I actually get, is that output1.mp4 has 2000 frames and lasts 33 seconds, but output2.mp4 has 2999 frames, and still lasts the full 50 seconds. When I open output2.mp4, I notice that the first 2000 frames of the video are actually just a repetition of the 2000th frame of the input, i.e. the first 2000 frames seem to be correctly filtered, but replaced by the first of the accepted frames.
This is not a pts problem. I check the number of packets and their relative pts using avprobe :
avprobe -show_packets output2.mp4
echo $(avprobe -show_packets output2.mp4 2>/dev/null | grep PACKET | wc -l)/2 | bcI see that there are actually 2999 packets.
What am I doing wrong ?
Side questions :
- Assuming I'm doing something wrong, why does output2.mp4 contain 2999 rather than the full 3000 ?
- The behaviour doesn't change whether I use the "gte" or "gt" function in the filter. Why could that be ?
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