[FFmpeg-cvslog] r22197 - trunk/libavformat/matroskaenc.c

[Måns Rullgård]

Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:

> On Thu, Mar 04, 2010 at 09:53:01AM +0100, conrad wrote:
>> Author: conrad
>> Date: Thu Mar  4 09:53:00 2010
>> New Revision: 22197
>> 
>> Log:
>> Attempt seeking to write EBML master sizes even if streamed
>> 
>> Most EBML masters are much smaller than IO_BUFFER_SIZE and thus the size
>> can be updated. This makes parsing the resulting files easier.
>> 
>> Modified:
>>    trunk/libavformat/matroskaenc.c
>> 
>> Modified: trunk/libavformat/matroskaenc.c
>> ==============================================================================
>> --- trunk/libavformat/matroskaenc.c	Thu Mar  4 05:58:43 2010	(r22196)
>> +++ trunk/libavformat/matroskaenc.c	Thu Mar  4 09:53:00 2010	(r22197)
>> @@ -218,11 +218,8 @@ static void end_ebml_master(ByteIOContex
>>  {
>>      int64_t pos = url_ftell(pb);
>>  
>> -    // leave the unknown size for masters when streaming
>> -    if (url_is_streamed(pb))
>> +    if (url_fseek(pb, master.pos - master.sizebytes, SEEK_SET) < 0)
>>          return;
>
> Is this "misuse" of fseek covered by our API specification?
> It assumes that seeking with url_is_streamed does never have a
> negative effect, however I'm not sure it couldn't be horribly
> slow or it might not keep the state the same or it might be possible
> to seek backward but seeking forward to the original position might fail...

Seeking within the buffer is always fast.  The seek function of the
underlying protocol is only invoked if the target is outside the buffer.

-- 
M?ns Rullg?rd
mans at mansr.com