[MEncoder-users] Accuracy of the -endpos option

[belcampo]

Josef Wolf wrote:
> On Tue, Jun 29, 2010 at 03:36:12PM +0200, belcampo wrote:
>> Josef Wolf wrote:
>>> On Mon, Jun 28, 2010 at 10:32:24PM +0200, belcampo wrote:
>>>> Josef Wolf wrote:
>>>>> On Mon, Jun 28, 2010 at 04:38:29PM +0200, belcampo wrote:
>>>>>> Josef Wolf wrote:
>>>>>>> Hello,
>>>>>>>
>>>>>>> I have troubles with the accuracy of the -endpos option. Most of the time,
>>>>>>> I get about 40 to 50 frames too much. When I adjust the value to get the
>>>>>>> correct end position, then audio ends about 2 seconds too early.
>>>>>> With ffmpeg -vframes ### you can exactly say how many frames you want.
>>>>>> The problem with -endpos or -t when using ffmpeg, it uses recording
>>>>>> duration, NOT video- or audio-duration but the smallest of them.
>>>>> Hmmm... Does mencoder have a counterpart to -vframes? I have gone a long way
>>>>> to optimize the codec settings for mencoder and would like to avoid to start
>>>> >from scratch when moving to ffmpeg...
>>>> If you post your command line settings, maybe it's easy translated
>>>> to ffmpeg, or use the solution explained further.
>>> Sure, I can post them:
>>>
>>>  mencoder \
>>>  -ss 00:00:01.880 -endpos 241.92 \
>>>  -vf yadif=0,crop=704:560:8:8,softskip,harddup \
>>>  -oac mp3lame -lameopts preset=medium -passlogfile \
>>>  -ovc x264 -x264encopts \
>>>  bitrate=800:pass=2:subq=7:frameref=15:me=umh:partitions=all:8x8dct:direct_pred=auto:me_range=64:trellis=2:bframes=5:weight_b:threads=auto:nr=1000:b_pyramid=normal:turbo=2 \
>>>  -passlogfile x264-800/2010-05-08-Tanz-Jan-3-Tanz.avi.log \
>>>  -o x264-800/2010-05-08-Tanz-Jan-3-Tanz.avi \
>>>  2010-05-09-Tanz-Jan008.avi
>>>
>>> Whatever I tried, I get much bigger files with very bad quality from ffmpeg.
> 
>> All those -ovc x264 -x264encopts ... and there ffmpeg equivalents,
>> they are the same, mencoder and ffmpeg use exactly the same x264
>> libraries, so there can't be any difference in that part.
> 
> While the options are the same, the syntax how to specify them is very
> different.
> 
>> http://rob.opendot.cl/index.php/useful-stuff/x264-to-ffmpeg-option-mapping/
> 
> Ah, thanks for this link. I think this was exactly what I was looking for.
> 
>> Could you provide a sample, an upload somewhere, of the source-file ?
> 
> I'll try to get the option mapping correct first. If I can't get it working,
> I'll upload samples. IIRC there was an upload area somewhere at mplayyhq.hu?
Yes but only to prove something is a bug.
> 
>> Some general thoughts, not knowing what kind of source yor dealing with.
>> me_range=64 where mewiki.project357.com/wiki/X264_Settings says
>> merange
>>
>> Default: 16
>>
>> merange controls the max range of the motion search in pixels. For
>> hex and dia, the range is clamped to 4-16, with a default of 16. For
>> umh and esa, it can be increased beyond the default 16 to allow for
>> a wider-range motion search, which is useful on HD footage and for
>> high-motion footage. Note that for umh, esa, and tesa, increasing
>> merange will significantly slow down encoding.
>>
>> frameref=15
>> Looks rather/very high to me
> 
> This is the highest possible value AFAIK. I am trying to get the highest
> possible quality with file size as short as possible because I encode for
> archival. I don't really care much about encoding time.
> 
>>> So demuxing, encoding/snipping, and muxing afterwards should also work fine?
>>> Last time I tried, mencoder refused to process a video stream without audio or
>>> an audio stream without video.
>> I'm used to use more then 1 application, I try to pick 'the best'
>> for a given task. Maybe it's not your piece of cake.
> 
> Normally, I also try to pick the best. But with video encoding it is very hard
> to find the best. There are so many applications, all use different syntax,
> and most of them use the same libraries under the hood. Selecting the "best"
> quickly turns out to be a full-time-job.
If it would pay well, one could considder ;-)
> _______________________________________________
> MEncoder-users mailing list
> MEncoder-users at mplayerhq.hu
> https://lists.mplayerhq.hu/mailman/listinfo/mencoder-users