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

[Misha Penkov]

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
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