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

[Eric Wescott]

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.

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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