Re: [FFmpeg-devel] [PATCH 2/4] avcodec/ccaption_dec: check the length of packet and return used length

[lance.lmwang@gmail.com]

On Thu, May 12, 2022 at 08:25:29AM +0200, Paul B Mahol wrote:
> On Thu, May 12, 2022 at 1:39 AM <lance.lmwang@gmail.com> wrote:
> 
> > On Wed, May 11, 2022 at 09:47:52PM +0200, Paul B Mahol wrote:
> > > why?
> >
> > assuming the len is 1, the following code will access the next 3
> > array anymore, I think it's better to check the i with len -2.
> >
> > for (i = 0; i < len; i += 3) {
> > to
> > for (i = 0; i < len - 2; i += 3) {
> >
> > for the return, I think it's correct to return the used length,
> > if it's error, have return already. right?
> 
> 
> I doubt so.

maybe I'm misunderstand it, but from the comments, the API claims that:
libavcodec/codec_internal.h
175          * @return amount of bytes read from the packet on success,
176          *         negative error code on failure
177          */
178         int (*decode)(struct AVCodecContext *avctx, struct AVFrame *frame,
179                       int *got_frame_ptr, struct AVPacket *avpkt);
180         /**
181          * Decode subtitle data to an AVSubtitle.
182          * cb is in this state if cb_type is FF_CODEC_CB_TYPE_DECODE_SUB.
183          *
184          * Apart from that this is like the decode callback.
185          */
186         int (*decode_sub)(struct AVCodecContext *avctx, struct AVSubtitle *sub,
187                           int *got_frame_ptr, const struct AVPacket *avpkt);

> >
> >
> > --
> > Thanks,
> > Limin Wang
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-- 
Thanks,
Limin Wang
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