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

[Francois Visagie]

> -----Original Message-----
> From: ffmpeg-user-bounces at ffmpeg.org [mailto:ffmpeg-user-
> bounces at ffmpeg.org] On Behalf Of Tim Nicholson
> Sent: 17 May 2013 10:13
> To: FFmpeg user questions
> Subject: Re: [FFmpeg-user] [Bulk] Muxer Catch-22 with '-target pal-dvd'
> 
> 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.

That's good info, thanks, Tim.

> --
> Tim
<< snip >>