[FFmpeg-devel] [PATCH] fixes in mpeg audio parsing

[Yoav Steinberg]

Michael Niedermayer wrote:
> On Thu, Nov 13, 2008 at 09:10:41PM +0200, Yoav Steinberg wrote:
>>
>> Michael Niedermayer wrote:
>>> On Thu, Nov 13, 2008 at 06:59:17PM +0200, Yoav Steinberg wrote:
>>> [...]
>>>>> One certainly could have concatenated 2 mp3 files with a id3v1 ending in
>>>>> the middle it would be nice if the parser & decoder would skip/ignore this
>>>>> trash in the middle.
>>>>> To me it seem that it shouldnt be too hard to make the parser skip
>>>>> this, unless a valid id3v1 tag can also be a valid mp3 frame.
>>>>>
>>>> The current parser will, in most cases, skip id3v1 tags in the stream 
>>>> which is good. But in one case the parser does actually think the tag is 
>>>> part of a frame and does not skip it. This is when the tag was put 
>>>> inside (overwriting) a frame's data. This isn't strictly valid, but it 
>>>> turns out there are such files out there.
>>> so, fix the parser
>> I don't see how the parser can detect such a case. If the tag data is 
>> inside the frame's data the parser will see a valid frame.
> 
> now i do not know if such case exists (maybe you could upload a sample?)
> but assuming one exists then removing the last 128 byte will give you
> a truncated frame. That does not appear more correct than leaving a
> valid frame there.
> 

A few samples uploaded to MPlayer/incoming/id3v1_tag_inside_last_frame