[Libav-user] avcodec_decode_audio4 yields silence (zero data)

[Misha Penkov]

I've solved my problem.  I wasn't updating the packet correctly in
between calls to decode.  Please disregard my previous message.

Michael

On 15 June 2012 20:50, Misha Penkov <misha.penkov at gmail.com> wrote:
> Hi,
>
> I'm playing around with the FFmpeg tutorials at
> (http://dranger.com/ffmpeg/) and trying to update them to the most
> recent version of FFmpeg.  I'm having problems decoding audio.  In
> particular, the entire data array of the AVFrame I pass in is zero
> after decoding.
>
> Here's the code around the problem area:
>
> int bytes_consumed;
> int got_frame;
> bytes_consumed =
>    avcodec_decode_audio4
>    (
>        aCodecCtx,
>        frame,
>        &got_frame,
>        &pkt
>    );
> if (got_frame)
> {
>    int bytes_decoded =
>        av_samples_get_buffer_size
>        (
>            NULL,
>            aCodecCtx->channels,
>            frame->nb_samples,
>            aCodecCtx->sample_fmt,
>            1
>        );
>    int sum = 0;
>    int i = 0;
>    for (i = i; i < bytes_decoded; ++i)
>        sum += abs(frame->data[0][i]);
>    fprintf(stderr, "sum: %d\n", sum);
>    return bytes_decoded;
> }
>
> The whole data array sums to zero every time, and I get silence as
> output.  I'm attaching my full source for reference.
>
> Why does this happen?  What am I doing wrong?
>
> ffmpeg version N-41103-g67b7631
> built on Jun  4 2012 17:00:05 with gcc 4.4.3
>
> Thank you in advance for your help.
>
> Cheers,
> Michael