[FFmpeg-user] [Bulk] Muxer Catch-22 with '-target pal-dvd'

[Tim Nicholson]

On 16/05/13 12:24, Francois Visagie wrote:
>> -----Original Message-----
>> From: ffmpeg-user-bounces at ffmpeg.org [mailto:ffmpeg-user-
>> bounces at ffmpeg.org] On Behalf Of Tim Nicholson
>> Sent: 07 May 2013 11:05
>> To: FFmpeg user questions
>> Subject: Re: [FFmpeg-user] [Bulk] Muxer Catch-22 with '-target pal-dvd'
>>
>> On 05/04/13 10:17, Francois Visagie wrote:
>>> Hi All,
>>>[..]
>>> However, when encoding 704-wide Rec.601 source like DV (perfectly
>>> legal resolution for DVD), this option causes distortion by forcing
>>> horizontal resolution to 720 pixels (see ticket 2434
>>> <https://ffmpeg.org/trac/ffmpeg/ticket/2434> ). Some background on
>>> Rec.601 sources and 704-pixel horizontal resolution at
>>> http://en.wikipedia.org/wiki/Pixel_aspect_ratio.
>>>
>>>
>>>
>>> The work-around in this case is _not_ to use '-target pal-dvd' but to
>>> specify the DVD-compliant encode using individual options, e.g.
>>>
>>> '-codec:a ac3 -b:a 128000 -codec:v mpeg2video -g 15 -bf 2 -bufsize
>>> 1835000 -b:v 6090000 -maxrate 9800000 -muxrate 10080000'.
>>>
>>
>> It is easier to still specify -target pal-dvd then afterwards overide the
> size
>> with -s 704x576.
> 
> That's an interesting suggestion, thanks. It would need to somehow go into
> my standard encode Windows batch process (used for both 720x576 as well as
> 704x576 encodes). It would need to determine at runtime when input is
> 704x576 and only specify the resize then. Could something like ffprobe be
> used for this detection in a batch file (my ffmpeg build came without it)?
> 
> Also, I'm not familiar with the resizer's behaviour; would it still perform
> an unwanted resize when the source is already at 704x576?
> 
>> [..]

If the size is already correct then no resizing will happen, you might
need to ensure you set the scalers interlace option correctly to ensure
that any resizing doesn't blend frames. Note that auto inserted scalers
default to progressive scaling.
-- 
Tim