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22nd March 2016, 15:45 | #1 | Link |
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Location: Berlin, Germany
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Create DVD compatible MPEG2 using FFMpeg
Any FFMpeg specialists out there?
After spending a couple of hours reading docs and googling for advice I figured that I might get some better answers here... My questions are about FFMpeg default values if I specify "-c:v mpeg2video" AND "-f mpeg2video" in my command line. First question: Is specifying "-f mpeg2video" in addidtion to the codec redundant? Or does this parameter force some additional settings? Next question: If I explicitly specify values for GOP size, number of B-Frames and for DC precision (like "-dc 10 -g 12 -bf 2") then my encode will be significantly slower than if I just omit these parameters. For DC precision I found that the default is 0 which makes no sense for DVD. But the resulting MPEG2 file still seems to be 100% DVD compliant. Does FFMpeg have some kind of "Auto Mode" if the "mpeg2video" parameter is used for the codec and/or for the format? And if so, which values will get used? Cheers manolito Last edited by manolito; 22nd March 2016 at 15:49. |
25th March 2016, 17:25 | #3 | Link |
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Sorry, this is not an option...
The FFMpeg MPEG2 encoder may be strange, but it sure spits out excellent quality when using the right parameters. I mainly need this information for my DVDStyler plugin (allows VBR and HQ encodes while DVDStyler by itself only does CBR). Cheers manolito |
25th March 2016, 18:30 | #4 | Link | ||
HCenc author
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AFAIK "-f mpeg2video" is redundant if "-c:v mpeg2video" is already specified.
Quote:
Settings for dc and gop length will not have a large impact on encoding speed. Quote:
Default in FFMPEG is "-dc 8" which is intra_dc_precision 0.
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HCenc at: http://hank315.nl |
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25th March 2016, 20:56 | #5 | Link | |
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Quote:
Did something change recently ? Used to produce terrible quality with any settings. No soft pulldown either for "24p" scenarios. |
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25th March 2016, 23:35 | #6 | Link | |
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Thanks very much Hank for the explanations...
Makes things a lot clearer for me. I did not know that FFMpeg by default does not create any B-Frames at all. All MPG2 encoders I have used so far do create B-Frames by default, so I thought that this is an agreed standard for MPEG2. While B-Frames might not be that useful for very high bitrates, they certainly make sense for medium and lower bitrates. @ poisondeathray The followqing two-pass parameters (courtesy of Fishman0919) do produce excellent results, at least for bitrates of 3500 and below. According to Fishman the results are superior to HCenc. Quote:
For soft pulldown you can use DGPulldown. Cheers manolito Last edited by manolito; 26th March 2016 at 00:39. |
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26th March 2016, 13:34 | #7 | Link | ||
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Quote:
Luckily this is not the case. I did a few test encodes using either "-dc 10" or "-dc 2", and in both cases a DC Precision value of 10 was reported (by MediaInfo and Restream). Seems like FFMpeg internally maps these values for MPEG2 encoding. BTW the default for -dc is not 8, but 0... Quote:
Cheers and thanks again manolito |
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