July 2010 - MEncoder-users - lists.mplayerhq.hu

Help with MPG video encoding
by Walter Belhaven 20 Apr '13

20 Apr '13

Hi, I've got a question on how to get the best possible MPG encoding of a movie source, "at any price" so to speak -- i.e., as many bits as the encoder needs to get the highest possible video quality. It appears to me that the MPG encoding process is introducing artifacts that are present regardless of the amount of "free reign" I give to the encoder with respect to quantization, bitrate, and the like. My bottom line question is thus: "Are these artifacts inherent in MPG encoding, or am I just not twiddling the knobs and dials on the encoder correctly?" Here's all the details ... My source is a mixed hard- and soft-telecined "movie" at 1080/60i that I'm trying to tanscode to 480/24p, soft telecined to 480/60i, for ultimate burning to an NTSC DVD-Video. When I use mencoder to inverse telecine, crop out the crud, expand back to the original letterbox ratio (it's 2.35:1, not 16/9), and 'encode' the video with HUFFYUV (422P), the resulting video looks stunning, with no 'blocking' artifacts to speak of. This, of course, is as expected. But when I encode the video in MPG2 or MPG4, even with vqscale=1 or vqscale=2, I see sometimes severe blocking in the resulting video. Is this because the chroma is being subsampled vertically and horizontally (4:2:0), or is it because 'vqscale' is (perhaps necessary but) not sufficient to get "maximum quality at any price" encoding? Thanks, WB ____________________________________________________________________________________ Be a PS3 game guru. Get your game face on with the latest PS3 news and previews at Yahoo! Games. http://videogames.yahoo.com/platform?platform=120121

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B-frames and GOP with MPEG-2 for DVD
by Nicolas Hesler 16 Apr '11

16 Apr '11

Can anyone offer any input to the following command line? I've been trying to refine for the highest possible quality of MPEG-2 while staying DVD compliant. The source is 24fps. (Note: format=mpeg2, because format=dvd does not work with Adobe Encore 2.0). From what I understand, keeping GOP open, improves quality. Is this true? Is it 100% DVD compliant? Do I want to introduce B frames in my encoding? (The vb_strategy part of my command line is currently useless, right?) If parts of my video are reaching into 9-10 Mbs bitrate, would it beneficial to introduce B-Frames? Will it improve quality? (This is probably a stupid question) Are the sync issues with bframes only relevant to mpeg4 or lavf? mencoder -oac lavc -ovc lavc -of mpeg -mpegopts format=mpeg2:tsaf:telecine / -vf scale=720:480,harddup -mc 0 -noskip -srate 48000 -af lavcresample=48000:0:2 -lavcopts / vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=7000:vbitrate=6000:keyint=12 / :trell:mbd=2:precmp=2:subcmp=2:cmp=2:dia=-10:predia=-10:cbp:mv0:vqmin=1:lmin=1 / :dc=10:vpass=1:vb_strategy=2:acodec=ac3:abitrate=224:aspect=16/9:vstrict=0 -ofps 24000/1001 -o $output $input

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Decoding h264
by double 25 Nov '10

25 Nov '10

Hi, "libavcodec" has problems with some h264 videos. Demuxing works, but not decoding. Is there a chance to use a native codec via the "-vc" switch? Testcase: mplayer http://doppelbauer.name/H264.mov Thanks a lot! Marcus

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Re: [MEncoder-users] cat /dev/video0 | mencoder - ...
by Bob Tennent 16 Aug '10

16 Aug '10

>| You don't even specify a bitrate or quality here. The man page lists >| the options available. The man page is virtually incomprehensible to anyone who doesn't already understand the technical issues. For example: I can see that there is an x264 option for bitrate. So what should I use? 10, 100, 10000, 10000000? How should I know? The default is *off*, whatever that means. By looking at the output, I can see that 1548.19 kb/s is what I get for a test run. Can I set it lower? How low would be right? Should I spend a week experimenting with all of the options? >| At a bare minimum, you'll want to specify rate control options. And which options would those be? I came here for help, not to be referred to the man page. I've looked for a comprehensible tutorial but there doesn't seem to be one.

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mencoder dvdnav:// encodes twice
by Tony Howard 05 Aug '10

05 Aug '10

Hi, I've been trying to encode encrypted DVDs using mencoder dvdnav://, and it mostly works, but it will rip the entire contents of the DVD twice to a single file... if it's a 2 hour movie, I'll end up with a 4 hour file that has the movie twice. Here's the command I've been using to rip them: mencoder dvdnav://1 -dvd-device /dev/dvd -alang English -info name="Meet The Colors" -oac copy -ovc x264 -x264encopts crf=26 -vf pp=de,crop=0:0:0:0,scale=1024:576 -o /home/video/meet_colors.avi I've seen this behavior on some (but not all) Disney DVDs, and several others as well. I'm using the rpmfuson mencoder from mencoder-1.0-0.111.20091029svn.fc12.i686.rpm on Fedora 12. Using -chapter 1-(something before the last chapter) works, but of course misses the chapters I leave out. Running mencoder dvd://1 also only encodes the movie once, but that just works for dvds that aren't encrypted. Anybody know how it to get dvdnav to only encode the movie once? Tony

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Re: [MEncoder-users] cat /dev/video0 | mencoder - ...
by Bob Tennent 31 Jul '10

31 Jul '10

>| the x264 preset option is explained thorough, no? No. The "explanation" consists only of listing what other option values the preset translates into. A user who is going to use a preset does so because they *don't* want to deal with all those complex options. What is missing (I see comparable remarks for *other* presets) is a simple statement that "fast" and "slow" etc. refer to the desired encoding speed, with corresponding loss/gain of quality. This may seem obvious to you and it's what I would have assumed except that someone in the thread suggested I use *slower* presets, presumably because he thought slower was for slower processors. More importantly, the preset option shouldn't be mixed in with dozens of more advanced technical options. A well-structured tutorial organized to present options in a sensible order (essential, important, advanced) and with a variety of use-case examples is badly needed. It took about 25 messages to the list before I converged on preset=faster as the solution to my problem and I don't think it's because I'm stupid, though I admit I dont know much about video encoding.

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Re: [MEncoder-users] cat /dev/video0 | mencoder - ...
by Bob Tennent 31 Jul '10

31 Jul '10

>| do the settings (slow, ..., fast, ...) refer to the desired encoding >| rate or to the speed of the processor? For the record, these settings refer to encoding speed. By increasing the settings from medium, I determined that "fast" wasn't fast enough but "faster" was. My problem seems solved. The problems with the documentation remain.

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dv1, dv2, raw ??
by Goga777 31 Jul '10

31 Jul '10

Hi I'm using dvgrab for capture of video from my dv camcorder (I'm using usb port). Which format (dv1, dv2, raw) better to use for mencoder with libx264 ? from dvgrab manpage - dv1 and dv2 both are AVI files with slightly different formats. dv2 stores a separate audio track in addition to the DV video track, which is more compatible with other applications. dv1 only stores a single, integrated DV track since the DV format natively interleaves audio with video. Therefore, while dv1 produces smaller output, some applications won’t grok it and require dv2 instead. dvgrab is capable of creating extremely large AVI files—well over 2 or 4 GB— however, compatibility with other tools starts to decrease over the 1 GB size. - raw stores the data unmodified and have the .dv extension. These files are read by a number of GNU/Linux tools as well as Apple Quicktime.

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Re: [MEncoder-users] cat /dev/video0 | mencoder - ...
by Bob Tennent 31 Jul '10

31 Jul '10

>|did you try to use x264 presets with mencoder as slow , slower, very >|slow ? >| >| --preset Use a preset to select encoding settings >| [medium] >| Overridden by user settings. >| - >| ultrafast,superfast,veryfast,faster,fast >| - medium,slow,slower,veryslow,placebo Please clarify: do the settings (slow, ..., fast, ...) refer to the desired encoding rate or to the speed of the processor? If I'm to avoid dropping frames, I surely want one of the fast (not slow) settings, unless the settings refer to the processor (an example of how the man page tells you everything except the most important thing).

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Re: [MEncoder-users] cat /dev/video0 | mencoder - ...
by Bob Tennent 31 Jul '10

31 Jul '10

>|Beginning with x264-encoding, I found this >| >|http://www.mplayerhq.hu/DOCS/HTML/en/menc-feat-x264.html >| >|not too bad to find the options I need. Thanks for the link. But Nearly all of this guide's comments assume you are using two pass. If I use mencoder /dev/video0 ... or cat /dev/video0 | mencoder - ... can I get "two pass"? My understanding of "two pass" is that two passes are made over a file.

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