[FFmpeg-devel] [PATCH] avcodec/gsm_parser: return -1 on parse error

James Almer jamrial at gmail.com
Wed Jan 30 23:57:08 EET 2019

On 1/30/2019 6:44 PM, Chris Cunningham wrote:
> On Wed, Jan 30, 2019 at 1:40 PM James Almer <jamrial at gmail.com> wrote:
>> Parsers can't return negative values, only the output packet size. For
>> the purpose of errors, they usually return the entire untouched packet
>> size.
> Understood. Is this documented somewhere? I noted the comment in
> av_paser_parse2(), "/* WARNING: the returned index can be negative */", and
> guessed that signaled an error.

    /* This callback never returns an error, a negative value means that
     * the frame start was in a previous packet. */
    int (*parser_parse)(AVCodecParserContext *s,
                        AVCodecContext *avctx,
                        const uint8_t **poutbuf, int *poutbuf_size,
                        const uint8_t *buf, int buf_size);

So i was wrong in that it's not that it can't return negative values,
just not for the purpose of signaling errors.

>> And this definitely means there's a bug elsewhere. This parser should
>> have not been used for codecs ids other than GSM and GSM_MS. That's
>> precisely what this assert() is making sure of.
> I'll take a closer look at how this parser was selected.
> Thanks for the quick reply.
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