September 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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mencoder: mp2->mp4 autoaspect question
by Toerless Eckert 10 Oct '10

10 Oct '10

I am using mencoder to convert TV mpeg2 recordings to mpeg4: -vc mpeg12 -ovc lavc -lavcopts vcodec=mpeg4:v4mv:autoaspect:... This works only to a degree: the mpeg4 file seems to get the aspect ratio that the mpeg2 input file has at the beginning (16:9 or 4:3), but when the aspect ratio changes within the input mpeg2 file, then this does not correctly gets translated into the mpeg4 file. What is see is that both xbmc and vlc will correctly switch to the initial aspect ratio at the beginning of the file, but not during the ongoing playback of the file. On the other hand, they do correctly change the aspect ratio while playing the original mpeg2 files. I encode the mpeg4 files with avi header, so the aspect ratio does not come from the file header. Is this supposed to work with mencoder ? If not, how difficult would it to add this to mencoder ? Thanks Toerless

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Need help for multi symbol huffman decoding for DVCPro-HD/DV100
by pcuser p 27 Sep '10

27 Sep '10

Hi, I am in process of optimizing DVCpro -HD decoder (SMPTE - 370M standard) in TI-C64X platform It's getting difficult to achieve target MIPS,The main bottleneck are IDCT and VLD. I am trying to get some info about multi symbol huffman decoding done for DV decoders. can any body suggest me a good link which explains multisymbol huffman decoders in context of DV

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Rotate video problem.
by vikas khairnar 26 Sep '10

26 Sep '10

Hello Friends, I am new to mencoder, rotating .flv video using it but I have one problem to rotate video after rotating video resulting video is to small If I have upload 14 sec. video resulting video is only of 2 seconds and speed is very fast. This is my command. $call = "/usr/local/bin/mencoder $infile -vf rotate=1 -oac copy -ovc lavc -lavcopts vcodec=flv -o $infile -of lavf -lavfopts format=flv"; $exec = shell_exec($call); return $exec; Can you please suggest me what to do?

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audio/video delay/async in an ogv file
by Erik Streb del Toro 24 Sep '10

24 Sep '10

Hello. I was trying the last couple of hours to get a OGG video in sync with it’s audio stream. The audio comes in to soon and needs delaying. I used: ffmpeg -i inputfile.ogv -itsoffset 00:00:00.6 -i inputfile.ogv -map 0:0 -map 1:1 -vcodec copy -acodec copy outputfile.ogv where both inputfiles are the same source with the audio delay problem. But the output file seems to be broken. If I set the offset to 10 seconds (00:00:10) you can see that even mplayer get’s stuck while playing. And vlc has some lags playing the file. And another strange thing: The length of the original input video is 31 seconds, but the output is also always 31 seconds (indifferent which value I put for itsoffset). Shouldn’t it get longer, with blank audio and blank video at the beginning and the end of the video file? I also tried it with mencoder: mencoder -audio-delay 0.6 inputfile.ogv -ovc copy -oac copy -o outputfile.ogv but that lead to a totally corrupted output file. Any suggestions on how to do this correctly? Erik PS: If you need a sample, you can just try it yourself, the video is on wikimedia commons: http://commons.wikimedia.org/wiki/File:ICE3_Schllenberg.ogg -- GPG-Schlüssel-ID: 0x036B38E6 Fingerabdruck: F057 EEEB F0F5 9144 D95C BD98 B822 138F 036B 38E6 Außerdem kann man per Jabber mit mir reden (chatten): Jabber-ID: wicking(a)jabber.org Off-The-Record: DEBD08C2 95E7C8CE 901EC136 E39A1E43 4FC13142

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convert to mp4 container
by ivo.linux 23 Sep '10

23 Sep '10

apologize me if someone will think that my question is stupid However I usually use the follow ffmpeg command to convert same videos for mi mobile phone ffmpeg -i MEGAVIDEO_-_Lo_sto_guardando.flv -acodec libfaac -ab 128kb -vcodec mpeg4 -b 1200kb -mbd 2 -flags +4mv -trellis 2 -cmp 2 -subcmp 2 -s 320x180 -metadata title=X output.mp4 my question is how I can obtain the same conversion with mencoder? Thanks in advance

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Hidden Intros in Videos
by Matt Shaw 19 Sep '10

19 Sep '10

Hey list, I've come across a weird problem - at least weird to me, since I don't deal with video that often. I'm trying to encode a batch of DV NTSC videos to H.264. When I watch the source video in Quicktime, I see 30 seconds of video. This is good. After I encode the video, I watch the mp4 and it is now 40 seconds long and it has a 10 second intro at the beginning. The intro is along the lines of "Bob's Test Promo #1234". It's not a generic promo that's somehow finding it's way into the encode. Each intro is specific to each video. 1) How does Quicktime know to ignore the first N seconds? It just completely pretends it's not there. This info must be in the video file headers or something. 2) Is there a name for this? I've had a hard time Googling "Hidden video intro" I'm aware that I can trim the video beginning of the video with -ss 00:00:10. The problem is that I have a ton of videos and the length of the intro varies (some don't have intros). So I'm looking for a way to automatically detect this intro (as Quicktime is able to) and trim accordingly. Thanks Matt

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nexus one dimension (pixels)
by hai yi 19 Sep '10

19 Sep '10

I wanted to use mencoder to convert a DVD to the right size mp4 file for my nexus one, I checked the specs and it says the size in pixels are 480X800, but doesnt it seem a little big? Seeing from the resulant video on the computer, it appears so. Still it can be squeezed in my nexus and it looks OK, might be a litlle wider, I don't know. Question is, what's the right size for nexus that I can set as mencoder's size option? Thanks, Hai

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