[FFmpeg-devel] [PATCH] avcodec/alsdec: properly allocate raw_buffer

Thilo Borgmann thilo.borgmann at mail.de
Sun Jul 2 17:03:20 EEST 2017

Am 01.07.17 um 03:38 schrieb Paul B Mahol:
> This also reverts 18f94df8.
> Fixes #5297.
> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> ---
>  libavcodec/alsdec.c | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
> [...]
> @@ -2062,7 +2057,7 @@ static av_cold int decode_init(AVCodecContext *avctx)
>      channel_size      = sconf->frame_length + sconf->max_order;
>      ctx->prev_raw_samples = av_malloc_array(sconf->max_order, sizeof(*ctx->prev_raw_samples));
> -    ctx->raw_buffer       = av_mallocz_array(avctx->channels * channel_size, sizeof(*ctx->raw_buffer));
> +    ctx->raw_buffer       = av_mallocz_array(avctx->channels * channel_size + sconf->max_order, sizeof(*ctx->raw_buffer));
>      ctx->raw_samples      = av_malloc_array(avctx->channels, sizeof(*ctx->raw_samples));

This looks like guessing only about a needed overhead to the raw buffer. What is
needed and actually done, is an overhead of max_order and that is already added
to the buffer length three lines above the proposed change. So this is nothing
more than guessing an overhead of 2*max_order should be enough but it does not
resolve knowingly any cause of the bug.

Therefore no, this still does not get applied until the actual reason of the bug
is found and properly fixed. I've got less time than I thought today and I could
not dive in as deep as I want. I cannot predict if there will be more time for
me to do it soon. So Paul, I'd appreciate if you could solve this bug but I will
only accept a proper patch and no guesswork.


p.s. I have the original pred.wav used by the ticket author and for me both
rm22rev2 and rm23 of the reference codec fail to decode pred.mp4 properly. Does
anyone else have the same problem with the reference codecs?

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