On Wed, Sep 7, 2011 at 2:46 PM, Laurent Aimar <fen...@elivagar.org> wrote:
> On Wed, Sep 07, 2011 at 02:43:48PM -0700, Alex Converse wrote:
>> > libavcodec/wavpack.c | 6 +++---
>> > 1 files changed, 3 insertions(+), 3 deletions(-)
>> >
>> > diff --git a/libavcodec/wavpack.c b/libavcodec/wavpack.c
>> > index 8e81d2d..f43819c 100644
>> > --- a/libavcodec/wavpack.c
>> > +++ b/libavcodec/wavpack.c
>> > @@ -1134,7 +1134,7 @@ static int wavpack_decode_block(AVCodecContext
>> > *avctx, int block_no,
>> > int16_t *dst = (int16_t*)samples + 1;
>> > int16_t *src = (int16_t*)samples;
>> > int cnt = samplecount;
>> > - while(cnt--){
>> > + while(cnt-- > 0){
>> > *dst = *src;
>> > src += channel_stride;
>> > dst += channel_stride;
>> > @@ -1143,7 +1143,7 @@ static int wavpack_decode_block(AVCodecContext
>> > *avctx, int block_no,
>> > int32_t *dst = (int32_t*)samples + 1;
>> > int32_t *src = (int32_t*)samples;
>> > int cnt = samplecount;
>> > - while(cnt--){
>> > + while(cnt-- > 0){
>> > *dst = *src;
>> > src += channel_stride;
>> > dst += channel_stride;
>> > @@ -1152,7 +1152,7 @@ static int wavpack_decode_block(AVCodecContext
>> > *avctx, int block_no,
>> > float *dst = (float*)samples + 1;
>> > float *src = (float*)samples;
>> > int cnt = samplecount;
>> > - while(cnt--){
>> > + while(cnt-- > 0){
>> > *dst = *src;
>> > src += channel_stride;
>> > dst += channel_stride;
>>
>> It's probably better to attack this closer to the root of the problem.
>> cnt is initialized to sample_count which is set by wv_unpack_mono()
>>
>> wv_unpack_mono() returns negative error codes so something like this
>> probably makes more sense:
>>
>>
>> > if(avctx->sample_fmt == AV_SAMPLE_FMT_S16)
>> > samplecount = wv_unpack_mono(s, &s->gb, samples,
>> > AV_SAMPLE_FMT_S16);
>> > else if(avctx->sample_fmt == AV_SAMPLE_FMT_S32)
>> > samplecount = wv_unpack_mono(s, &s->gb, samples,
>> > AV_SAMPLE_FMT_S32);
>> > else
>> > samplecount = wv_unpack_mono(s, &s->gb, samples,
>> > AV_SAMPLE_FMT_FLT);
>>
>> + if (samplecount < 0)
>> + return samplecount;
>
> Well not really, I think that the last part of the function, ie
>
> wc->samples_left = s->samples_left;
>
> should still be executed.
>
Why? If we return an error from wavpack_decode_block() (which happens
from either approach) it's caller (wavpack_decode_frame()) will short
circuit and return -1 and on its next invocation it will zero out
samples_left from the WavpackContext (Called wc in decode_block but s
in decode_frame).
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