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

Patrick Cusack patrickcusack at mac.com
Sat Apr 2 20:38:57 CEST 2016


This doesn’t direct;y answer your question, but look through the source code at this link:

http://www.gamedev.net/topic/624876-how-to-read-an-audio-file-with-ffmpeg-in-c/

This code will take you through parsing an audiostream. A couple of calls are deprecated but you can replace them easily enough.

On Apr 2, 2016, at 11:34 AM, Haris PP <harispp786 at gmail.com> 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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