[FFmpeg-devel] [RFC/PATCH] Dealing with 0 padded audio packets

[Michael Niedermayer]

On Tue, May 18, 2010 at 06:16:35PM -0400, Alex Converse wrote:
> Currently the FFmpeg stumbles when decoding AAC where the container
> has zero padded audio frames to make a constant packet size. This
> situation is common for AAC in ASF[1] and WMP handles it fine.
> QuickTime seems to handle the MP4 analog fine.
> 
> The best idea I can come up with is a chomp[2] bitstream filter to
> trim these when remuxing and to make the AAC decoder consume the rest
> of a packet if it is all zero.
> 
> Other ideas are welcome.

i wish i had a better idea, but i dont.
no real objections from me on this, just 2 nitpicks below


[...]
>  
> @@ -2065,6 +2066,12 @@ static int aac_decode_frame(AVCodecContext *avccontext, void *data,
>          ac->output_configured = OC_LOCKED;
>  
>      buf_consumed = (get_bits_count(&gb) + 7) >> 3;
> +    i = buf_consumed;
> +    while (i < buf_size && !buf[i])
> +        i++;
> +    if (i == buf_size)
> +        buf_consumed = buf_size;
> +
>      return buf_size > buf_consumed ? buf_consumed : buf_size;

this can be done less convoluted i think

[...]
> +static int chomp_filter(AVBitStreamFilterContext *bsfc,
> +                        AVCodecContext *avctx, const char *args,
> +                        uint8_t  **poutbuf, int *poutbuf_size,
> +                        const uint8_t *buf, int      buf_size,
> +                        int keyframe)
> +{
> +    int i = buf_size;
> +    while (i > 0 && !buf[i-1])
> +        i--;
> +
> +    *poutbuf = (uint8_t*) buf;
> +    *poutbuf_size = i;

you dont need i, buf_size should do

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Old school: Use the lowest level language in which you can solve the problem
            conveniently.
New school: Use the highest level language in which the latest supercomputer
            can solve the problem without the user falling asleep waiting.
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