[FFmpeg-devel] [RFC][PATCH] ticks_per_frame / timebase

[Baptiste Coudurier]

Michael Niedermayer wrote:
> On Thu, Feb 26, 2009 at 02:18:41PM -0800, Baptiste Coudurier wrote:
>> Hi guys,
>>
>> Michael Niedermayer wrote:
>>> On Thu, Feb 26, 2009 at 10:05:28PM +0100, Ivan Schreter wrote:
>>>> Michael Niedermayer wrote:
>>>>> [...]
>>>>> also i think the reset of the sei vars should be in
>>>>> decode_nal_units()
>>>>> ...
>>>>>     if(!(s->flags2 & CODEC_FLAG2_CHUNKS)){
>>>>>         h->current_slice = 0;
>>>>>         if (!s->first_field)
>>>>>             s->current_picture_ptr= NULL;
>>>>>         <-----------------------here
>>>>>     }
>>>>>
>>>>> the reason is that just reseting at the end of a pic is "risky" if that 
>>>>> end
>>>>> isnt reached
>>>>>
>>>>>   
>>>> Like in the attached patch?
>>> yes, patch ok
>>>
>>> btw, if you want a svn write account, (and agree to the devel/svn policy
>>> and split patches a little more, this one should be
>>> factorizing the code and then seperately adding the new call)
>>> then send diego b. some username & password gpg encrypted
>>>
>> Applied both patches:
>>
>> ffmpeg -i h264.mp4 -vcodec copy test.mov
>>
>> Seems stream 1 codec frame rate differs from container frame rate: 12.50
>> (25/2) -> 25.00 (25/1)
>> Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'H264.mp4':
>>   Duration: 00:00:02.18, start: 0.000000, bitrate: 2245 kb/s
>>     Stream #0.0(eng): Audio: aac, 44100 Hz, stereo, s16
>>     Stream #0.1(eng): Video: h264, yuv420p, 720x576, 25 tbr, 25 tbn, 25 tbc
>> File 'test.mov' already exists. Overwrite ? [y/N] y
>> Output #0, mov, to 'test.mov':
>>     Stream #0.0(eng): Video: libx264, yuv420p, 720x576, q=2-31, 90k tbn,
>> 25 tbc
>>     Stream #0.1(eng): Audio: libfaac, 44100 Hz, stereo, s16, 64 kb/s
>>
>> Is this supposed to report 12.50 ?
> 
> no, ive droped the hunk that messed with the printing in ffmpeg.c locally
> is the nonsense it prints the only problem? or are there other problems?
> 

It seems ok, however it does not do the same for MPEG-2 when I stream copy:

Seems stream 0 codec frame rate differs from container frame rate: 25.00
(50/2) -> 25.00 (25/1)
Input #0, mpeg, from 'PubMatrix.mpg':
  Duration: 00:00:24.26, start: 0.220000, bitrate: 11888 kb/s
    Stream #0.0[0x1e0]: Video: mpeg2video, yuv422p, 720x608 [PAR 1:1 DAR
45:38], 11386 kb/s, 25 tbr, 90k tbn, 50 tbc
    Stream #0.1[0x1c0]: Audio: mp2, 48000 Hz, stereo, s16, 384 kb/s
File 'test.mov' already exists. Overwrite ? [y/N] y
Output #0, mov, to 'test.mov':
    Stream #0.0: Video: mpeg2video, yuv422p, 720x608 [PAR 1:1 DAR
45:38], q=2-31, 11386 kb/s, 90k tbn, 50 tbc
    Stream #0.1: Audio: libfaac, 48000 Hz, stereo, s16, 64 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1

In this case pkt->duration is 2 and timebase.den is 50, with H.264
pkt->duration is 1 and timebase.den is 25, is this normal ? Can't we get
1 and 1/25 with MPEG-2 too ?

It seems for H264 the codec timebase for encoding is adjusted.

-- 
Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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