[FFmpeg-devel] [RFC] use ff_avc_find_startcode in ff_find_start_code

Måns Rullgård mans
Tue Feb 19 16:20:07 CET 2008


Reimar D?ffinger wrote:
> Hello,
> On Tue, Feb 19, 2008 at 03:06:37PM -0000, M?ns Rullg?rd wrote:
>> Reimar D?ffinger wrote:
>> > On Tue, Feb 19, 2008 at 03:28:27PM +0100, Reimar D?ffinger wrote:
>> >> For decoding my THX_Science_FLT_1920.gxf, ff_find_start_code in
>> >> mpeg_decode_frame
>> >> is called 73754 times for 353 frames, the average amount of data skipped is
>> >> 1272.626343 bytes.
>> >
>> > And uh... yes, this does indeed mean that 90% of the file's data is
>> > trash...
>> > Probably there is not much point in concentrating on this kind of thing,
>> > but I'd expect these kind of long skips might be common for DVDs in
>> > order to try to get a more constant bitrate as well...
>>
>> DVDs generally use the standard MPEG2-PS padding stream, so this should
>> not be an issue there.
>
> I checked that btw., with DVDs there usually (more than 50% of cases) is
> a 5 byte skip and then the start code.
> But the Spaceballs DVD has an skip of 140 byte on average in the first
> 10 minutes, going down to an average of 70 later on.

Where are these skips?

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




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