[FFmpeg-devel] [PATCH] Fix non-rounding up to next 16-bit aligned bug in IFF decoder

[Måns Rullgård]

Sebastian Vater <cdgs.basty at googlemail.com> writes:

> Sebastian Vater a ?crit :
>> I have fixed the wrong IFF decoding issue in the IFF decoder.
>>
>> The reason is that the IFF docs say that each line in the BODY chunk has
>> it's width rounded up to next 16-bit boundary, such that each new line
>> begins on a word boundary (address divisible by 2).
>>
>> Please review and apply.
>>
>> I will do the heavy optimization stuff now based on this.
>>   
>
> So, since there were changes in git/svn because unsigned => signed, my
> earlier patches regarding this won't work anymore.
>
> So, here's an updated version.
>
> -- 
>
> Best regards,
>                    :-) Basty/CDGS (-:
>
> diff --git a/libavcodec/iff.c b/libavcodec/iff.c
> index be13f4e..7af3d37 100644
> --- a/libavcodec/iff.c
> +++ b/libavcodec/iff.c
> @@ -72,7 +72,7 @@ static av_cold int decode_init(AVCodecContext *avctx)
>          return AVERROR_INVALIDDATA;
>      }
>  
> -    s->planesize = avctx->width >> 3;
> +    s->planesize = FFALIGN(avctx->width, 16) >> 3; // Align plane size in bits to word-boundary
>      s->planebuf = av_malloc(s->planesize + FF_INPUT_BUFFER_PADDING_SIZE);
>      if (!s->planebuf)
>          return AVERROR(ENOMEM);
> @@ -99,7 +99,7 @@ static void decodeplane8(uint8_t *dst, const uint8_t *const buf, int buf_size, i
>  {
>      GetBitContext gb;
>      int i;
> -    const int b = (buf_size * 8) + bps - 1;
> +    const int b = buf_size * 8;
>      init_get_bits(&gb, buf, buf_size * 8);
>      for(i = 0; i < b; i++) {
>          dst[i] |= get_bits1(&gb) << plane;
> @@ -118,7 +118,7 @@ static void decodeplane32(uint32_t *dst, const uint8_t *const buf, int buf_size,
>  {
>      GetBitContext gb;
>      int i;
> -    const int b = (buf_size * 8) + bps - 1;
> +    const int b = buf_size * 8;
>      init_get_bits(&gb, buf, buf_size * 8);
>      for(i = 0; i < b; i++) {
>          dst[i] |= get_bits1(&gb) << plane;

If this works, I have no objections from a style or performance POV.

-- 
M?ns Rullg?rd
mans at mansr.com