[FFmpeg-devel] [PATCH] [ISSUE 793] Fix mp3 identification regressions

[Alex Converse]

On Sat, Jan 31, 2009 at 5:26 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Fri, Jan 30, 2009 at 08:01:25PM -0500, Alex Converse wrote:
>> On Fri, Jan 30, 2009 at 4:46 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> > On Thu, Jan 29, 2009 at 12:31:52PM -0500, Alex Converse wrote:
>> >> On Thu, Jan 29, 2009 at 12:28 PM, Alex Converse <alex.converse at gmail.com>wrote:
>> >>
>> >> > Right now MP3 files with ID3v2 tags bigger than 2MB no longer identify as
>> >> > MP3. This patch makes the mp3 probe return 1 on files with id3v2 tags where
>> >> > mp3 was not identified to make these files identiy as MP3 on the last probe
>> >> > pass. A more elegant solution would be for the probes to be able to request
>> >> > seeking, however it seems that that would piss all over the API. I know
>> >> > Michael had suggested a return value to request more data in general but in
>> >> > theory ID3v2 can grow over 256 MB and I'm nto sure we'd want to sent that
>> >> > much information to the probe.
>> >> >
>> >>
>> >> I suppose it might be helpful if I actually attach the patch.
>> >
>> > iam not against this patch id just like to make sure you understand that
>> > it will not be nearly as reliably as you might think, other codecs also
>> > make wild guesses and return 1 on random data on occasion
>> >
>>
>> I see what you are saying here. The old code used to give us
>> AVPROBE_SCORE_MAX/2+1 on all files that had id3v2 tags. Do you think
>> return AVPROBE_SCORE_MAX/4-1 would be appropriate for any file with an
>> id3v2 tag?
>
> its probably better than 1, still best would be to fix the probe API to
> allow formats to request more data.
>

I agree that there needs to be a structural change to the probe API
but I don't think requesting more data is the answer. Two megabytes is
a lot of data. I think it needs to be allowed to request a seek.

For the time being I'd like commit the patch attached in this message
if no one objects.

--Alex
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