[MEncoder-users] Audio sync problems with HDV footage while performing an inverse telecine

[Alexander Strange]

On May 4, 2010, at 3:44 PM, Eric Wescott wrote:

> Using "filmdint=io=30:24/fast=0,softskip,harddup,scale=1920:1080 -noskip"? produces some strange color artifacts on the top 50 or so lines of pixels. You can see the detail but it's like there are sections where a green/purple filter is put over it. It's not constant and flickers and seems random where these filters are placed.
> 
> What exactly is the different between filmdint and pullup? 
> I had a similar problem when using vcodec=huffyuv instead of vcodec=ffvhuff. Using huffyuv would produce a similar problem on random clips but on the bottom of the frame. It however lost the entire detail and just looked almost like a visualization of the audio but didn't actually correspond to the audio playing.
> 
> Anyway, I seem to have found the solution by removing the -mc 0 section and sticking with ffvhuff.
> 
> 
> Maybe one more thing to note.. After I get the 24p huffyuv version I'm transcoding it in Final Cut Studio's Compressor application to ProRes 422 and ProRes 422 Proxy. Some files aren't recognized by Compressor (I suspect it's a bug in Perian) and I can detect this by finder not showing a thumbnail preview for this file.

Do you have a sample or reliable way to create one for this?

> My solution is for these few files that don't work (maybe 50 out of the 5,000) I just encode them as x264 lossless and it does the trick. The only reason I didn't do it for all the files in the first place is it's much slower to transcode from x264->ProRes than Huffy->ProRes..
> 
> 
> Thanks
> Eric
> 
> 
> 
> Laine Lee wrote:
>> On 5/3/10 1:22 AM, "Eric Wescott" <wescotte at gmail.com> wrote:
>> 
>>  
>>> I have about ~5,000 HDV files recorded using an Canon HV30 Camera set to
>>> it's HD 24F mode. In order to get a proper 24P video file you need to
>>> perform a inverse telecine. I'm using the following method to create huffyuv
>>> files which I then transcode again into Apple ProRes for use in Final Cut
>>> Pro. The page
>>> http://eugenia.gnomefiles.org/2007/07/13/canon-hv20-24p-pulldown/ lists
>>> several methods to perform the inverse telecine process but mencoder seems
>>> to be the only one to do it correctly for me. JES-Deinterlacer produces some
>>> strange video artifacts..
>>> 
>>> Anyway, I'm having some issues where some of the files have audio sync
>>> issues. Sometimes it's just off by a constant rate like and I just shift it
>>> in Final Cut and it's fine. Other times the file starts in sync and then
>>> gradually looses sync. I'd say about 10-20% of the files have audio sync
>>> problems. Here is my current process
>>> 
>>> mencoder  INPUT.m2t -noskip -fps 30000/1001 -vf
>>> pullup,softskip,harddup,scale=1920:1080 -ofps 24000/1001 -ovc lavc -lavcopts
>>> vcodec=ffvhuff:autoaspect -oac pcm -o OUTPUT.avi
>>> 
>>> ALSO, If I perform a
>>> 
>>> mencoder INPUT.m2t -ovc copy -oac copy OUTPUT.mpeg
>>> 
>>> and then transcode to huffy will produce different results and sometimes
>>> produce a correct final output.
>>> 
>>> I've tried the most recent builds and a few older ones.. I seem to have the
>>> same results. I originally followed the guide at
>>> 
>>> 
>>> Any suggestions?
>>>    
>> 
>> 
>> If you can copy audio with the 2nd example, have you tried it with the
>> first?
>> 
>> I've had much better success with filmdint than I've ever had with pullup.
>> It depends entirely on the source, of course, but what happens if you use
>> 
>> "filmdint=io=30:24/fast=0,softskip,harddup,scale=1920:1080 -noskip"?
>> 
>> Maybe you could use Socke's ffmpeg-sox pipe that adjusts ac3 audio tempo. To
>> raise the pitch slightly (shorten duration), the tempo adjustment factor is
>> higher than 1. You have to demux and work on the audio, then remux. I put in
>> the brackets because the first occurrence of sox is actual (not a path)
>> 
>> ffmpeg -v 0 -i input.ac3 -f sox - | [/usr/local/bin/]sox -S -V -p -p tempo
>> 1.00003 | ffmpeg -v 0 -i - -acodec ac3 -ab 448000 -y adjusted_tempo_out.ac3
>> 
>> Play the video and use plus and minus keys to correct audio sync once near
>> beginning then once near end. For example, if audio has to be moved ahead
>> 500 milliseconds (500 on the mplayer on screen display, 5 presses of the
>> plus key), subtract .5 from the total number of seconds of audio, then
>> divide the original number of seconds of audio by that number to get the
>> tempo adjustment factor.
>> 
>> I created an AppleScript droplet to calculate that and perform the operation
>> that can be downloaded with the other AppleScript droplets here:
>> 
>> http://lonestar.utsa.edu/llee/HDTV_to_DVD.html
>> 
>> Laine Lee
>> 
>> 
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>>  
> 
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