[Libav-user] ffmpeg audio data for ploting wave form

Stephane Poirier stephane.poirier at oifii.org
Sat Apr 2 21:03:33 CEST 2016


Hi Haris,

Here's a little program I did to draw audio waveform on various 
backgrounds. It is C code however.

http://www.oifii.org/ns-org/nsd/ar/cp/audio_spi/spiffmpegmuxingspectrum_qt2016/spiffmpegmuxingspectrum-RGB24_qt2016.c

Steph


On 02/04/2016 2:34 PM, Haris PP wrote:
> Hi,
>
> I need to plot wave form of audio as explained here 
> http://stackoverflow.com/questions/16509906/ffmpeg-can-i-draw-an-audio-channel-as-an-image, 
> I found that some command line option for plotting to image, but my 
> requirement is do from c++ code and draw live waveform on UI. I am 
> able to decode the audio data successfully, but no idea how the data 
> is stored in `AVFrame` `extended_data` pointer. The audio can be 
> either stereo or mono.
>
>     AVFrame *frame=av_frame_alloc();
>     while(av_read_frame(container,&packet)>=0)
>      {
>
>         int len=avcodec_decode_audio4(ctx,frame,&frameFinished,&packet);
>         frame->extended_data //how data stored inside the pointer
>         ........................
>     }
>
>
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