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VOB to MP4

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VOB to MP4

Kyle Schwarz
Hello, I have several TV shows that are in standard VOB NTSC format. I want
to get them into .MP4 format with x264 encoded video, and faac encoded
audio.

When I first tested it the interlaced lines were appearing, so I ran it
again with the -deinterlace command this time. The interlace bars were gone
but it had a odd playback lag which made it seem like it was skipping past
frames and such.

When I first started to backup my TV shows I used a program called "Gordian
Knot" and I remember I ran into the same issue. The fix for it in Gordian
Knot was to check a option called "IDCT" I believe.

So, I then passed -idct 0 in my command line and took out the -deinterlace,
but still the problem remains. Is there any way to fix this or what should I
be doing to encode my NTSC video into a 23.976 frame rate .MP4?

I am using FFmpeg version FFmpeg SVN-r23341 and the command line I was using
was:

./ffmpeg -i Infile.vob -vframes 1000 -vcodec libx264 -deinterlace -fpre
> '../share/ffmpeg/libx264-hq.ffpreset' -b 883k -bt 883k -s 512x384 -vsync 1
> -r 23.976 -aspect 4:3 -acodec libfaac -ab 128k -ac 2 -ar 44100 Outfile.mp4
>

Also, the MediaInfo for the VOB is:

General

> Format                           : MPEG-PS
> File size                        : 955 MiB
> Duration                         : 23mn 38s
> Overall bit rate                 : 5 648 Kbps
>
> Video
> ID                               : 224 (0xE0)
> Format                           : MPEG Video
> Format version                   : Version 2
> Format profile                   : Main@Main
> Format settings, BVOP            : Yes
> Format settings, Matrix          : Default
> Format settings, GOP             : M=3, N=15
> Duration                         : 23mn 38s
> Bit rate mode                    : Variable
> Bit rate                         : 5 087 Kbps
> Nominal bit rate                 : 7 500 Kbps
> Width                            : 720 pixels
> Height                           : 480 pixels
> Display aspect ratio             : 4:3
> Frame rate                       : 29.970 fps
> Standard                         : NTSC
> Color space                      : YUV
> Chroma subsampling               : 4:2:0
> Bit depth                        : 8 bits
> Scan type                        : Interlaced
> Scan order                       : Top Field First
> Bits/(Pixel*Frame)               : 0.491
> Stream size                      : 861 MiB (90%)
>
> Audio
> ID                               : 128 (0x80)
> Format                           : AC-3
> Format/Info                      : Audio Coding 3
> Mode extension                   : CM (complete main)
> Duration                         : 23mn 38s
> Bit rate mode                    : Constant
> Bit rate                         : 448 Kbps
> Channel(s)                       : 5 channels
> Channel positions                : Front: L C R, Side: L R
> Sampling rate                    : 48.0 KHz
> Video delay                      : -67ms
> Stream size                      : 75.7 MiB (8%)
>
> Text
> ID                               : 224 (0xE0)-DVD-2
> Format                           : EIA-608
> Muxing mode                      : MPEG Video / DVD-Video
> Muxing mode, more info           : Muxed in Video #1
> Stream size                      : 0.00 Byte (0%)
>

Any ideas on how to fix this?
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Re: VOB to MP4

Mike Scheutzow-2
Kyle Schwarz wrote:

> Hello, I have several TV shows that are in standard VOB NTSC format. I want
> to get them into .MP4 format with x264 encoded video, and faac encoded
> audio.
>
> When I first tested it the interlaced lines were appearing, so I ran it
> again with the -deinterlace command this time. The interlace bars were gone
> but it had a odd playback lag which made it seem like it was skipping past
> frames and such.
>
> When I first started to backup my TV shows I used a program called "Gordian
> Knot" and I remember I ran into the same issue. The fix for it in Gordian
> Knot was to check a option called "IDCT" I believe.
>
> So, I then passed -idct 0 in my command line and took out the -deinterlace,
> but still the problem remains. Is there any way to fix this or what should I
> be doing to encode my NTSC video into a 23.976 frame rate .MP4?
>
> I am using FFmpeg version FFmpeg SVN-r23341 and the command line I was using
> was:
>
> ./ffmpeg -i Infile.vob -vframes 1000 -vcodec libx264 -deinterlace -fpre
>  
>> '../share/ffmpeg/libx264-hq.ffpreset' -b 883k -bt 883k -s 512x384 -vsync 1
>> -r 23.976 -aspect 4:3 -acodec libfaac -ab 128k -ac 2 -ar 44100 Outfile.mp4
>>
>> [...]
>> Any ideas on how to fix this

1) The frame skipping is happening because the input .vob is 29.97
frames/sec, but you've told h264 to encode the video at 23.97
frames/sec. The simplest way the video encoder can accomplish that is by
dropping video frames. The fix is choose a preset with a video frame
rate of 29.97 (and use default -vsync parameter.)

2) At a low video bitrate like 883 kbits/sec, you should try an output
size of 480x240 (i.e. half of vertical input size) and see if the result
looks OK to you. It will depend, in part, on how big a window you use
when you watch it. As a happy side effect, using vertical size 240
should clean up the ugly comb-teeth effect due to the interlaced input.
Using this vertical size, you shouldn't need -deinterlace.

3) You'll get better video quality if you don't specify a video bitrate,
but instead use a -crf value. Try a value of 22. The general rule is:
the higher this number, the smaller your output file size.

--
Mike Scheutzow


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Re: VOB to MP4

Kyle Schwarz
In reply to this post by Kyle Schwarz
>
> 1) The frame skipping is happening because the input .vob is 29.97
> frames/sec, but you've told h264 to encode the video at 23.97
> frames/sec. The simplest way the video encoder can accomplish that is by
> dropping video frames. The fix is choose a preset with a video frame
> rate of 29.97 (and use default -vsync parameter.)
>
>
I know that when I encoded with Gordian Knot, which uses Xvid I could get a
23.976 rate without having any problem with dropped frames. Is there any way
to do this with FFmpeg?
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