[FFmpeg-devel] [Ffmpeg-user] chroma errors on movie file.

[Baptiste Coudurier]

Hi

Michael Niedermayer wrote:
>>>>>>
>>>>>> [...]
>>>>>>
>>>>>>Ok, problem is that "fiel" atom parsing overwrites extradata in
>>>>>>mov_read_extradata (overwrite 'SMI ' atom), so decoder fails to decode
>>>>>>stream. Attached patch makes mov_read_extradata appending atoms in
>>>>>>extradata. svq3 decoder will search for 'SEQH' sequence (contained in
>>>>>>'SMI ') in extradata.
>>>>>>
>>>>>>Michael is it ok for you ?
>>>>>
>>>>>
>>>>>yes, except:
>>>>>
>>>>>[...]
>>>>>
>>>>>>Index: libavformat/mov.c
>>>>>>===================================================================
>>>>>>--- libavformat/mov.c	(revision 10249)
>>>>>>+++ libavformat/mov.c	(working copy)
>>>>>>@@ -470,14 +470,25 @@
>>>>>>static int mov_read_extradata(MOVContext *c, ByteIOContext *pb, MOV_atom_t atom)
>>>>>>{
>>>>>>   AVStream *st = c->fc->streams[c->fc->nb_streams-1];
>>>>>>+    uint8_t *data_ptr;
>>>>>>+    if (st->codec->extradata) {
>>>>>>+        unsigned old_size = st->codec->extradata_size;
>>>>>>+        if((uint64_t)atom.size > (1<<30) - old_size - 8)
>>>>>>+            return -1;
>>>>>
>>>>>
>>>>>this check
>>>>>if old_size for example is 1<<30 this check fails
>>>>>
>>>>
>>>>Humm it's late but if old_size is 1<<30 it must indeed fail, because new
>>>>atom size won't be < 1<<30. Or ?
>>>
>>>
>>>lets say it more precissely, the return -1 wont be executed if old_size=1<<30
>>>
>>
>>Ok I see it now, what about that ?
> 
> 
> it might work but its a little obfuscated
> 

Aie, well a bit :(
I can merge both tests, and add comments to explain why we are appending
atoms but code speaks for itself no ?

Do you have a suggestion ? I'll code it, this bug needs to be fixed.

-- 
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