[FFmpeg-devel] [PATCH 2/2] ADP demuxer

[James Almer]

On 24/04/13 12:01 AM, Michael Niedermayer wrote:
> in that case you could test all the headers within 260+ bytes instead
> of just 2
> 
> 
>> valid frame to avoid tiertexseq files being misdetected as adp (The first 256 bytes 
>> are all 0 on tiertexseq).
>> If buf_size is < 260 and the probe for tiertexseq succeeds, then the probe for adp 
>> will succeed as well. Making adp return a lower score than tiertexseq in that case 
>> will make sure tiertexseq is chosen.
>>
>> I'll make it return 0 if that's preferred, though.
> 
> i think 1 is better
> returning 0 for short adp files doesnt feel correct

Would something like this be ok?

    if (p->buf_size < 32)
        return 0;

    for (i = 0; i < p->buf_size - 3; i+=32)
        if (p->buf[i] != p->buf[i+2] || p->buf[i+1] != p->buf[i+3])
            return 0;

    return p->buf_size < 260 ? 1 : AVPROBE_SCORE_MAX / 4;

>>
>>>> +    if (s->pb->seekable)
>>>> +        st->duration          = avio_size(s->pb) / 32 * 28;
>>>
>>> Is this check needed ?
>>> avio_size() should harmlessly fail if the protocal cant seek
>>
>> Many other demuxers check for pb->seekable before calling avio_seek() or avio_size(),
>> so i figured it was the proper way to handle this.
>> Personally, I'd like to keep it this way.
> 
> whichever way you prefer
> 
> 
>>
>>>> +AVInputFormat ff_adp_demuxer = {
>>>> +    .name           = "adp",
>>>> +    .long_name      = NULL_IF_CONFIG_SMALL("ADP"),
>>>> +    .read_probe     = adp_probe,
>>>> +    .read_header    = adp_read_header,
>>>> +    .read_packet    = adp_read_packet,
>>>> +    .extensions     = "adp,dtk",
>>>> +};
>>>
>>> does seeking work with this demuxer ?
>>> (also see AVFMT_GENERIC_INDEX)
>>
>> Doesn't look like, even after adding that flag "ffmpeg -ss 1 -i sample.adp" warns 
>> that it couldn't seek.
> 
> hmm
> probably would make sense to compare with a other simple demuxer that
> can seek

I can't seem to find anything different in other simple demuxers that has any effect
here.