[Libav-user] infinite loop in avcodec_encode_audio when encoding AAC

[Josh Gargus]

Unfortunately I'm on Windows, and setting up a build environment for both libav and it's prerequisite libraries is a bit of a hassle.  

Do you consider this patch to be The Right Thing?  A hacky workaround?  The reason I ask is that if I can just wait a few days or weeks for it to show up in a nightly build, then I'll wait.  But, if there's no chance of having the patch accepted as-is, then I'll have to think about other options.

Cheers,
Josh



On Aug 7, 2011, at 3:41 AM, avcoder wrote:

> It's the bug of aacenc encoder in FFmpeg, try the following patch
> 
> --- aacenc.c	Thu Jan 15 17:14:12 1970
> +++ aacenc.c	Thu Jan 15 17:14:12 1970
> @@ -573,6 +573,8 @@
>         }
>         start_ch += chans;
>     }
> +
> +    s->last_frame_bits = 0;
>     do {
>         int frame_bits;
>         init_put_bits(&s->pb, frame, buf_size*8);
> @@ -639,6 +641,10 @@
>             s->psy.bitres.bits = frame_bits / avctx->channels;
>             break;
>         }
> +        //it seems that lambda is broken
> +        if (s->last_frame_bits == frame_bits)
> +            break;
> +        s->last_frame_bits = frame_bits;
> 
>         s->lambda *= avctx->bit_rate * 1024.0f / avctx->sample_rate /
> frame_bits;
> 
> --- aacenc.h	Thu Jan 15 17:14:12 1970
> +++ aacenc.h	Thu Jan 15 17:14:12 1970
> @@ -72,6 +72,7 @@
>     float lambda;
>     DECLARE_ALIGNED(16, int,   qcoefs)[96];      ///< quantized coefficients
>     DECLARE_ALIGNED(32, float, scoefs)[1024];    ///< scaled coefficients
> +    int last_frame_bits;
> } AACEncContext;
> 
> #endif /* AVCODEC_AACENC_H */
> 
> 
> On Sat, Aug 6, 2011 at 1:26 PM, Josh Gargus <josh at schwa.ca> wrote:
>> I'm running into a problem that seems essentially the same as:
>> http://stackoverflow.com/questions/2410459/encode-audio-to-aac-with-libavcodec
>> … except that I'm already encoding at a far lower bitrate than the threshold
>> that started to cause him problems (I encode at 64000bits/sec, and he was OK
>> below 386000bits/sec).
>> Has anyone else seen anything else like this?  I'll be happy to provide more
>> details if anyone is interested.
>> Thanks,
>> Josh
>> _______________________________________________
>> Libav-user mailing list
>> Libav-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/libav-user
>> 
>> 
> 
> 
> 
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