[FFmpeg-user] PAL MP4 displays VITC in transcodes

[Mark Himsley]

On 31/12/2012 17:43, marcus at sonicpool.com wrote:
>
> Hello Mark
> 

Hello Markus,

On this email list it is preferred that you don't reply at the top of
the email but reply in-line or at the bottom. Outlook does not make that
easy, but there are add-ons which help. The mailing list rules
explained on http://ffmpeg.org/contact.html

I have moved your reply to the bottom, where I respond...

>> -------- Original Message --------
>> Subject: Re: [FFmpeg-user] PAL MP4 displays VITC in transcodes
>> From: Mark Himsley <mark at mdsh.com>
>> Date: Sat, December 29, 2012 4:00 am
>> To: FFmpeg user questions <ffmpeg-user at ffmpeg.org>
>> Cc: marcus at sonicpool.com
>> 
>> 
>> On 29/12/2012 01:54, marcus at sonicpool.com wrote:
>>> Hello All
>>>
>>> I'm fairly young to FFMPEG but I'm coming across an unusual problem.
>>> I've been encoding various (NTSC) QT ProsRes HQ to mp4. So far no
>>> problems.
>>> When using very similar settings for my (PAL) QT ProRes, the end results
>>> are unusual.
>>>
>>> I'm seeing VITC TIMECODE and additional "blanking" in the (PAL) mp4's.
>>> The source files of 
>>> the active picture don't have any visible VITC and no blanking. However
>>> once I've transcoded the file, it is severely shifted. Displaying VITC &
>>> Blanking in the final product. Please see attachment. 
>>>
>>> I've checked the files in MEDIA INFO to verify the resolution.
>>> The QT ProRes is 720x576 5:4 and the MP4 is reporting 720x608 5:4
>>> Is there away transcode only Active Lines?
>> 
>> <SNIP>
>> 
>>> Stream #0:1(eng): Video: mpeg2video (4:2:2) (mx5p / 0x7035786D),
>>> yuv422p, 720x608 [SAR 152:135 DAR 4:3], 50000 kb/s, SAR 16:15 DAR 24:19,
>>> 25 fps, 25 tbr, 25 tbn, 50 tbc
>> 
>> What you have here is 'PAL' IMX50 video - MPEG2 I-Frame only at 50Mbps.
>> 
>> (I'm using 'PAL' to mean 25 FPS Standard Definition)
>> 
>> For those who don't know, 'PAL' IMX50 is, as you can see, 720x608. That
>> is 720x576 with 32 lines of VBI (Vertical Blanking Interval) at the top,
>> which may include VITC (Vertical Interval Time Code).
>> 
>> So Marcus, you want to use the crop filter in FFmpeg.
>> 
>> Your bare minimum command would be:
>> 
>> ./ffmpeg -i /Volumes/XXXXXX/XXXX/PAL/TJB_WTextless_PAL_ENG.mov -r 25 -vf
>> crop=720x576:0:32 JungleBook/TJB_WTextless_PAL_ENG/video.mp4
>> 
>> Hope that helps.
>
> That was the solution to my problem :)
> Previously, I had done a test at home on my Ubuntu station. Using the
> settings from before. It didn't produce the same problem on my MAC.
>
> It's strange FFMPEG is seeing the ProRes QuickTime (720x576) as if it's
> IMX-50 resolution.
>
> Hope this gets fixed in the near future

I'm quite confident that the media IS IMX50 and there is nothing to fix.
What do other tools, such as mediainfo, say about your file?

/Volumes/XXXXXX/XXXX/PAL/TJB_WTextless_PAL_ENG.mov

If you think there is a bug then can you open a ticket and attach your
problematic file?

Thanks.

-- 
Mark