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  • Encoding video only FLV

    25 mars 2012, par NadavRub

    I am trying to generate a video only FLV file, I am using :

    1. libx264 + ffmpeg
    2. 30 fps ( fixed )
    3. playback is done using VLC 2.0.1 and flowplayer

    When playing the FLV the frame-rate seems 1 frame per sec, following is the way I cfg ffmpeg :

    AVOutputFormat* fmtOutput = av_oformat_next(0);
    
while((0 != fmtOutput) && (0 != strcmp(fmtOutput->name, "flv")))
    
    fmtOutput = av_oformat_next(fmtOutput);
    
m_pFmtCtxOutput          = avformat_alloc_context();
    
m_pFmtCtxOutput->oformat = fmtOutput;
    

    
AVStream* pOutVideoStream= av_new_stream(m_pFmtCtxOutput, pInVideoStream->id);
    
AVCodec*  videoEncoder   = avcodec_find_encoder(CODEC_ID_H264);
    

    
pOutVideoStream->codec->width    = 640;
    
pOutVideoStream->codec->height   = 480;
    
pOutVideoStream->codec->level    = 30;
    
pOutVideoStream->codec->pix_fmt  = PIX_FMT_YUV420P;
    
pOutVideoStream->codec->bit_rate = 3000000;
    

    
pOutVideoStream->cur_dts         = 0;
    
pOutVideoStream->first_dts       = 0;
    
pOutVideoStream->index           = 0;
    
pOutVideoStream->avg_frame_rate  = (AVRational){ 30, 1 };
    
pOutVideoStream->time_base       =
    
pOutVideoStream->codec->time_base= (AVRational){ 1, 30000 };
    
pOutVideoStream->codec->gop_size = 30;
    
%% Some specific libx264 settings %%
    
m_dVideoStep                     = 1000;// packet dts/pts is incremented by this amount each frame
    

    
pOutVideoStream->codec->flags   |= CODEC_FLAG_GLOBAL_HEADER;
    
avcodec_open(pOutVideoStream->codec, videoEncoder);

    The resulting file seems OK, with the exception of the playback frame-rate.
    having in mind that :

    1. pOutVideoStream->avg_frame_rate = (AVRational) 30, 1  ;
    2. pOutVideoStream->time_base = (AVRational) 1, 30000  ;
    3. pOutVideoStream->codec->time_base= (AVRational) 1, 30000  ;
    4. For each frame I increment the dts/pts by 1000

    What am I doing wrong here ? why the file is playing choppy ( 1 fps ) ?

    Any help will be appreciated.

    Nadav at Sophin

  • Encoding video only FLV

    25 mars 2012, par NadavRub

    I am trying to generate a video only FLV file, I am using :

    1. libx264 + ffmpeg
    2. 30 fps ( fixed )
    3. playback is done using VLC 2.0.1 and flowplayer

    When playing the FLV the frame-rate seems 1 frame per sec, following is the way I cfg ffmpeg :

    AVOutputFormat* fmtOutput = av_oformat_next(0);
    
while((0 != fmtOutput) && (0 != strcmp(fmtOutput->name, "flv")))
    
    fmtOutput = av_oformat_next(fmtOutput);
    
m_pFmtCtxOutput          = avformat_alloc_context();
    
m_pFmtCtxOutput->oformat = fmtOutput;
    

    
AVStream* pOutVideoStream= av_new_stream(m_pFmtCtxOutput, pInVideoStream->id);
    
AVCodec*  videoEncoder   = avcodec_find_encoder(CODEC_ID_H264);
    

    
pOutVideoStream->codec->width    = 640;
    
pOutVideoStream->codec->height   = 480;
    
pOutVideoStream->codec->level    = 30;
    
pOutVideoStream->codec->pix_fmt  = PIX_FMT_YUV420P;
    
pOutVideoStream->codec->bit_rate = 3000000;
    

    
pOutVideoStream->cur_dts         = 0;
    
pOutVideoStream->first_dts       = 0;
    
pOutVideoStream->index           = 0;
    
pOutVideoStream->avg_frame_rate  = (AVRational){ 30, 1 };
    
pOutVideoStream->time_base       =
    
pOutVideoStream->codec->time_base= (AVRational){ 1, 30000 };
    
pOutVideoStream->codec->gop_size = 30;
    
%% Some specific libx264 settings %%
    
m_dVideoStep                     = 1000;// packet dts/pts is incremented by this amount each frame
    

    
pOutVideoStream->codec->flags   |= CODEC_FLAG_GLOBAL_HEADER;
    
avcodec_open(pOutVideoStream->codec, videoEncoder);

    The resulting file seems OK, with the exception of the playback frame-rate.
    having in mind that :

    1. pOutVideoStream->avg_frame_rate = (AVRational) 30, 1  ;
    2. pOutVideoStream->time_base = (AVRational) 1, 30000  ;
    3. pOutVideoStream->codec->time_base= (AVRational) 1, 30000  ;
    4. For each frame I increment the dts/pts by 1000

    What am I doing wrong here ? why the file is playing choppy ( 1 fps ) ?

    Any help will be appreciated.

    Nadav at Sophin

  • avconv much longer than ffmpeg

    18 mars 2014, par fsulser

    I was using ffmpeg to generate some images from a video. Now I read that I shouldn't use ffmpeg longer and use avconv from libav instead.
    So I tried to do the same thing with avconv.

    The ffmpeg is looking like this :

    ffmpeg -ss 1000 -t 5 -i 'test.mp4' -s '120*90' -r 10 out%2d.bmp

    Same with avconv :

    avconv -ss 1000 -t 5 -i 'test.mp4' -s '120*90' -r 10 out%2d.bmp

    ffmpeg needs less than one second to finish. Avconv about 90 seconds for the same task.
    Is this usual or do I need to change some things to work with avconv ?

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