[FFmpeg-user] deinterlacing with ntsc-dvd

[Matthew Morgan]

On 05/22/2013 11:29 AM, Francois Visagie wrote:
>> -----Original Message-----
>> From: ffmpeg-user-bounces at ffmpeg.org [mailto:ffmpeg-user-
>> bounces at ffmpeg.org] On Behalf Of Matthew Morgan
>> Sent: 22 May 2013 14:41
>> To: FFmpeg user questions
>> Subject: Re: [FFmpeg-user] deinterlacing with ntsc-dvd
>>
>> On 05/22/2013 08:08 AM, Francois Visagie wrote:
>>>> -----Original Message-----
>>>> From: ffmpeg-user-bounces at ffmpeg.org [mailto:ffmpeg-user-
>>>> bounces at ffmpeg.org] On Behalf Of Matthew Morgan
>>>> Sent: 22 May 2013 13:08
>>>> To: ffmpeg
>>>> Subject: [FFmpeg-user] deinterlacing with ntsc-dvd
>>>>
>>>> I'm having trouble with some material I'm converting to DVD with
>>>> ffmpeg; there is significant ghosting on some players, and some
>>>> google searches
>>> have
>>>> pointed out that this is often related to interlacing.
>>>>
>>>> The source materialis interlaced, top-field dominant, but when I run
>>>> it throughffmpeg using "-target ntsc-dvd", mediainfo shows the output
>>>> as being progressive.
>>>>
>>>> Here is my ffmpeg command line:
>>>>
>>>> ffmpeg -i dora_fairytale_cut.mpg -pass 1 -target ntsc-dvd -b:v 4000K
>>>> /dev/null && ffmpeg -i dora_fairytale_cut.mpg -pass 2 -target
>>>> ntsc-dvd
>>> -b:v
>>>> 4000K dora_fairytale_cut_compressed.mpg ffmpeg version N-53018-
>>>> ge70e258 Copyright (c) 2000-2013 the FFmpeg developers
>>>>   built on May 13 2013 07:50:37 with gcc 4.6 (Ubuntu/Linaro
>>> 4.6.3-1ubuntu5)
>>>>   configuration: --prefix=/opt/mmedia --enable-libxvid --enable-gpl
>>> --enable-
>>>> libtheora --enable-libmp3lame --enable-libfaac --enable-nonfree
>>>> --enable-
>>>> libv4l2 --enable-x11grab --enable-libvpx
>>>>   libavutil      52. 30.100 / 52. 30.100
>>>>   libavcodec     55.  9.100 / 55.  9.100
>>>>   libavformat    55.  7.100 / 55.  7.100
>>>>   libavdevice    55.  0.100 / 55.  0.100
>>>>   libavfilter     3. 65.100 /  3. 65.100
>>>>   libswscale      2.  3.100 /  2.  3.100
>>>>   libswresample   0. 17.102 /  0. 17.102
>>>>   libpostproc    52.  3.100 / 52.  3.100
>>>> [mpeg @ 0xa43ae00] max_analyze_duration 5000000 reached at 5024000
>>>> microseconds [NULL @ 0xa43b780] start time is not set in
>>>> estimate_timings_from_pts Input #0, mpeg, from
>> 'dora_fairytale_cut.mpg':
>>>>   Duration: 00:46:56.26, start: 0.500000, bitrate: 6569 kb/s
>>>>     Stream #0:0[0x1bf]: Data: dvd_nav_packet
>>>>     Stream #0:1[0x80]: Audio: ac3, 48000 Hz, stereo, fltp, 448 kb/s
>>>>     Stream #0:2[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x480
>>>> [SAR
>>> 8:9
>>>> DAR 4:3], 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc File '/dev/null'
>>> already exists.
>>>> Overwrite ? [y/N] y Output #0, dvd, to '/dev/null':
>>>>   Metadata:
>>>>     encoder         : Lavf55.7.100
>>>>     Stream #0:0: Video: mpeg2video, yuv420p, 720x480 [SAR 8:9 DAR
>>>> 4:3],
>>> q=2-
>>>> 31, pass 1, 4000 kb/s, 90k tbn, 29.97 tbc
>>>>     Stream #0:1: Audio: ac3, 48000 Hz, stereo, fltp, 448 kb/s Stream
>>> mapping:
>>>>   Stream #0:2 -> #0:0 (mpeg2video -> mpeg2video)
>>>>   Stream #0:1 -> #0:1 (ac3 -> ac3)
>>>> Press [q] to stop, [?] for help
>>>> frame=84404 fps=107 q=3.4 Lsize= 1562918kB time=00:46:56.28
>>>> bitrate=4546.2kbits/s dup=8 drop=0 video:1375112kB audio:154016kB
>>>> subtitle:0 global headers:0kB muxing overhead 2.209759%
>>>>
>>>> My question is, should I be specifying any kind of options to make
>>>> the deinterlacing happen correctly?  Is this even likely to be my
>>>> problem?  If
>>> you
>>>> need it, I can also post mediainfo output for the source and output
> files.
>>> PS. The options ' -flags ildct+ilme' _preserve_ interlacing. This is
>>> accepted by the DVD standard and incurs least quality loss.
>> Thanks!  Where in the command line should I put this?  After `-target
> ntsc-
>> dvd`?
> I normally do, to prevent my options being overridden by macro settings such
> as -target.
>
Just in case anyone else on this list has had the same ghosting problem, preserving the interlacing DOES fix it!  I did have to add `-top 1` to get it to mark it as top-field-first, but otherwise Francois' flags were perfect.  So it's all in one place, here's my command now:

ffmpeg -y -i dora_map_cut.mpg -pass 1 -target ntsc-dvd -b:v 4000K -flags ildct+ilme -top 1 /dev/null &&  ffmpeg -y -i dora_map_cut.mpg -pass 2 -target ntsc-dvd -b:v 4000K -flags ildct+ilme -top 1 dora_map_cut_compressed.mpg

My question now is what do these flags actually do:  prevent a deinterlacing filter from being run, or simply change what the header info says?  Without the flags is the output video still interlaced but incorrectly marked as progressive?