-target pal-dvd incorrectly forces 704x576 to 720x576

[Francois Visagie]

Summary of the bug:
The '-target pal-dvd' option incorrectly scales 704x576/480 to 720x576/480. For Rec.601-sourced video with 59:54 pixel aspect ratio a horizontal resolution of 704 pixels is required to produce undistorted output to 4:3 and 16:9 display aspect ratios. The DVD Video standard makes provision for authoring in this resolution, e.g. ​http://en.wikipedia.org/wiki/Dvd_video and ​http://www.videohelp.com/dvd. However, this behaviour (of '-target pal-dvd' at least) makes it impossible to produce undistorted output.
How to reproduce:

C:\Users\fvisagie\Videos\Home Videos\Testing\Sony DCR-TRV330E>ffmpeg -i New.avs -target pal-dvd -aspect 4:3 New.avs.mpg
ffmpeg version N-51511-g599866f Copyright (c) 2000-2013 the FFmpeg developers
  built on Apr  1 2013 12:44:46 with gcc 4.8.0 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
le-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libilbc --enable-libmp3lame --enable-libopencore-amrnb --enable-libo
pencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-lib
twolame --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  libavutil      52. 24.100 / 52. 24.100
  libavcodec     55.  2.100 / 55.  2.100
  libavformat    55.  1.100 / 55.  1.100
  libavdevice    55.  0.100 / 55.  0.100
  libavfilter     3. 48.105 /  3. 48.105
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  2.100 / 52.  2.100
Guessed Channel Layout for  Input Stream #0.1 : stereo
Input #0, avisynth, from 'New.avs':
  Duration: 00:01:57.28, start: 0.000000, bitrate: 0 kb/s
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 704x576, 25 fps, 25 tbr, 25 tbn, 25 tbc
    Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
Output #0, dvd, to 'New.avs.mpg':
  Metadata:
    encoder         : Lavf55.1.100
    Stream #0:0: Video: mpeg2video, yuv420p, 720x576 [SAR 16:15 DAR 4:3], q=2-31, 6000 kb/s, 90k tbn, 25 tbc
    Stream #0:1: Audio: ac3, 48000 Hz, stereo, fltp, 448 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo -> mpeg2video)
  Stream #0:1 -> #0:1 (pcm_s16le -> ac3)
Press [q] to stop, [?] for help
frame= 2933 fps= 22 q=2.0 Lsize=   80944kB time=00:01:57.31 bitrate=5652.3kbits/s dup=1 drop=0
video:72936kB audio:6414kB subtitle:0 global headers:0kB muxing overhead 2.009441%

Work-around:
Omit -target pal-dvd and use other options to specify a DVD-compliant encode on the command line, e.g. '-codec:a ac3 -b:a 128000 -vcodec mpeg2video -g 15 -bf 2 -bufsize 1835000 -b:v 6090000 -maxrate 9800000 -muxrate 10080000'.

[Francois Visagie]

For the DVD-compliant command line I meant to say:
'-codec:a ac3 -b:a 128000 -codec:v mpeg2video -g 15 -bf 2 -bufsize 1835000 -b:v 6090000 -maxrate 9800000 -muxrate 10080000'

However, this work-around does bring about the problem of Ticket 1720 (https://ffmpeg.org/trac/ffmpeg/ticket/1720), that of audio being unplayable by many applications. Work-arounds for playback are to use other players like Media Player Classic or to remultiplex in another application first. Applications like Avidemux also won't be able to demux files like this for authoring, in which case ffmpeg or another demuxer could be used instead.

"For Rec.601-sourced video with 59:54 pixel aspect ratio a horizontal resolution of 704 pixels is required to produce undistorted output to 4:3 and 16:9 display aspect ratios." - and for 16:9 DAR the PAR is 118:81 of course, just to prevent any avoidable confusion :).

[Carl Eugen Hoyos]

Replying to francois.visagie@…:

The '-target pal-dvd' option incorrectly scales 704x576/480 to 720x576/480.

This sounds unclear:
Does '-target pal-dvd' really scale 704x480 to 720x480? Or does it always scale to 720x576?
I suspect what you want - that -target pal-dvd sometimes scales to 704x576 and sometimes to 720x576 is not possible, but adding another target - pal-dvd-narrow - should be trivial, patch welcome.

[Francois Visagie]

Replying to cehoyos:

Replying to francois.visagie@…:

The '-target pal-dvd' option incorrectly scales 704x576/480 to 720x576/480.

This sounds unclear:
Does '-target pal-dvd' really scale 704x480 to 720x480? Or does it always scale to 720x576?
I suspect what you want - that -target pal-dvd sometimes scales to 704x576 and sometimes to 720x576 is not possible, but adding another target - pal-dvd-narrow - should be trivial, patch welcome.

In my testing 'target pal-dvd' scales 704x576 to 720x576, and leaves 720x576 untouched. 704x576 _is_ PAL DVD - as is 720x576 - so what I want is for 'target pal-dvd' to leave both 704x576 and 720x576 unchanged. Which is what I think would make sense to other users in general.