April 2008 - 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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2pass: auto-calculation of bitrate?
by Ilya Zakharevich 25 Nov '08

25 Nov '08

I'm looking for a way to let mencoder (I use xvid) to automatically select the 2-pass average video bitrate based on the contents. I'm pretty sure that most (if not the all) of the logic to do it is already there, but I can't find the UI to trigger this behaviour. A) For example: suppose I have 100 videos; now a) append them all together; b) do 2-pass encoding of them all with, e.g., 1200kb/sec bitrate; c) split the result into 100 video files. This way, mencoder will automatically assign some "appropriate" average bitrate to each video. B) Now suppose that I have only 1 video, but I have all 100 logs of pass=1 for all 100 videos. Theoretically, this is all which is needed to do an equivalent of a/b/c for this particular video. How to convince mencoder to use these extra log files? C) Now suppose that I have only 1 video, and only 1 log of pass=1 for this video. It is more or less obvious that all I need from the remaining 99 logs is very short "summaries". How to create the summaries, and how to "feed" them to mencoder? D) And now the last logical step: If of these 99 remaining videos 40% is "action-like", 40% is "arthouse-like", and 20% is animation, then law of big numbers starts to be applicable. Essentially, I won't need to have summaries of the particular videos; I could feed in 40 copies of "average action-like summary", 40 copies of "average arthouse-like summary", and 20 copies of "average animation summary". So if I keep these summaries in ~/.mplayer in action.sum arthouse.sum animation.sum, then I could ask mencoder to do bitrate_from=1200,40*action+40*arthouse+20*animation and it could choose the appropriate bitrate. Is it possible to do now (possibly, with some pre-processing)? Any plans to have this? Thanks, Ilya

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How to avoid A/V synchronisation pb
by Philippe MONROUX 05 May '08

05 May '08

Hi, First I apologize for my poor english. My goal is to x264 2-pass encode one dvd title to one 700 M cd with ogg vorbis sound (not very original...) So in first I need to rip sound to know its size (SoundSize) to have better bitrate calculation (700-SoundSize)*1024^2*8/t/1000 I've read the doc but I'm not sure about my method to avoid A/V synchronisation pbs. Here is my method : 1) rip audio to audio.ogg --> SoundSize --> bitrate 2) pass 1 : mencoder dvd://1 -aid 128 -oac copy -vf [filters] -ovc x264 -x264encopts [options-pass1]turbo=2:pass=1 -o /dev/null 3) pass 2 : mencoder dvd://1 -aid 128 -oac copy -vf [filters] -ovc x264 -x264encopts [options-pass2]:pass=2 -o out.avi 4) mkv creation... My question is about "-ovc copy" in pass-1 and pass-2. Is it a good choice to A/V synchronisation pbs or is there a better choice (I read nosound is not a good choice). Thanks in advance -- Mxph

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Mencoder does not cut exactly
by TAJTHY Tamás 01 May '08

01 May '08

Hi, I have a strange problem. I have a mjpeg avi file and I'd like to cut a part from it and convert to mpeg4. I detected the frames by VirtualDub. I did the following: mencoder ..compression-arguments.. -ss 1.120 -endpos 1:23:00.000 -o cut.avi patch.avi; My problem is that the resulted file does not contain the exact frames. Depending on the -ss option it can be +/-1 frames different. At the end position can be +/- 4 frames different. If I add 3-5 ms to the -ss and -endpos options so the start become puntual, but the problem still appears at the end. Could anybody help me how could I cut the exact frames I need? Thanks in Advance!

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Better mp4 container support being worked on?
by Bruno Hertz 30 Apr '08

30 Apr '08

Hi guys anybody knowing whether better libavformat, especially mp4, muxing support is being worked on? Right now it seems to be pretty much broken ... I know the docs says mencoder was built around avi, but I guess muxing into more advanced containers (mp4,mkv) is something quite some people would love being able to. Reason I ask is that I use mencoder for tv grabbing and would very much like to encode the stream into AVC/AAC. Putting that into an avi file obviously doesn't make much sense. And muxing into mp4 even without using bframes or any advanced x264 settings gives invalid files right now. If I could find another cmdline app which did grabbing that well as mencoder I wouldn't ask, but it's just so good at it - and many other things - that those format constraints really become a severely limiting factor. Thanks, Bruno.

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VHS to DVD
by Gugão 30 Apr '08

30 Apr '08

Hi all, I´m new in this list ! so has anyone a mencoder script to capture from VHS to DVD ? (i think is mpeg2) so i´ve tried some scripts and Skipping frame occurs during capture... thanks any help

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mp4 audio slipping when played back in Quicktime
by Nicolas Hesler 30 Apr '08

30 Apr '08

I've successfully created an MP4 with mencoder using the following command line. The file plays back normally using VLC but when played back in Quicktime, the audio slips by a couple of frames after about a minute. Any idea why this might be happening and how I might be change my command line options to make Quicktime happy? Note: I'm frameserving from Premiere and so my source should not inherently have a sync issue. (or so i assume) and my video source is only about a minute long, so the slippage is noticeable by the end of the video. mencoder -of lavf -sws 9 -lavfopts format=mp4 -vf dsize=1280:720:0,scale=0:0,expand=1280:720,harddup -ovc x264 -x264encopts bitrate=5000:qcomp=0.7:qp_min=1:direct_pred=auto:keyint=48:partitions=all:me=umh:subq=7:frameref=8:trellis=2:global_header:pass=1:psnr -oac faac -faacopts mpeg=4:object=2:br=224:raw -channels 2 -srate 48000

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FLV Playback Issue
by dragon＠gamerstube.com 30 Apr '08

30 Apr '08

I have users uploading WMV3 encoded files to my video hosting site. However the playback is terrible for users trying to watch the videos. The latest addition I captured from the video folder to examine. here are the specs: format: WMV3 size: 1280x720 fps: 1,000 bitrate: 7,000 kbps See the video: http://tinyurl.com/3n6r9c I am being told that it could be a codec issue on our server side. We are using 1.0rc1 with Clip-Share 2.6 PRO and the Agriaya FLV player. Thanks in advance. -Joe

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muxed vs. unmuxed/demuxed mpeg clarification
by Nicolas Hesler 30 Apr '08

30 Apr '08

My understanding is that Mencoder uses timestamp information to try to maintain sync when encoding. The DVD authoring program DVD Studio Pro for the mac only accepts unmuxed m2v and audio files. This prompted me to wonder... 1. Is video editing software (such as Final Cut Pro) able to make unmuxed files that are perfectly resyncable? In this case, is the video and audio treated seperately and therefore there is no danger of having sync issues when remuxing the files in a DVD authoring program? Is it because the audio/video are being served up raw from the software? 2. Is it only when you are transcoding compressed muxed files that you can are liable to lose sync? 3. Is sync guaranteed or otherwise better if you go from uncompressed windows AVI (other video formats?) to separate m2v and audio files? Any help on clarifying this issue is much appreciated.

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