- MEncoder-users - lists.mplayerhq.hu

Trimming video
by Pete Davis 26 Jun '05

26 Jun '05

Does mencoder provide any way to cut out sections of video? In particular, I just got a Hauppauge WinTV PVR 150 and after a few hours struggling to get the audio working, I was able to do some captures from my TiVo and came up with an encoding script that does a very nice job. Now I just need to be able to trim out the commercials. I played around with VirtualDub (in Windows) which makes it very easy to edit the video. Unfortunately it won't work directly with the mpg file. I need to encode to an AVI first (or else let VirtualDub do the encoding itself which I don't want it to do). It supports stream copying, but it doesn't seem to support creating key frames. Thus, I end up with cuts where I don't want them or really nasty video at the cuts I see MPlayer has the Edit Decision List, but it looks like MEncoder doesn't have an equivalent, or if it does, I missed it. At the very least, if there's a way for me to specify where to create key frames, that would at least let me do clean edits with VirtualDub. Is there another app I should be using? I hate to use more tools than I need. I want to stick with mencoder for the actual encoding because it does such a nice job and I'm getting more comfortable with it. Thanks.

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real-time encoding of DVB-S @ 900 MHz
by Moritz Beller 26 Jun '05

26 Jun '05

Hello there, I can pipe MPEG-2 streams from my Budget DVB-S card directly via cat /dev/dvb/adapter0/dvr0 > stream.ts to a file stream.ts, which can then simultaneously be watched with mplayer, the cat process occupying only few system resources. I could equally well play the stream directly with mplayer at 70% CPU usage, using the dvb://-syntax. That's all really well, but when it comes to recording video, it's got an extreme disadvantage: The raw format produces much too large files. So I clearly need to do some encoding, even scaling the video's size down would be ok, if only I could get the file smaller. I tried all different kinds of video codes (such as MPEG-4 at a bit rate of 40!), but couldn't figure out one sole which resulted in a CPU usage minor than 99%. I perform the decoding task on a Pentium III 900 MHz, so I should at least be able to real-time encode with medium-quality settings, shouldn't I? (With Mythtv I can even both watch and record, so there *must* be a way to achieve encoding with mencoder as well) What settings can you recommend? Thanks a lot indeed, Moritz -- (o_ web http://www.4momo.de //\ mail momo at 4momo dot de V_/_ gpg http://gpg.notlong.com

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(work-in-progress) XviD encoding guide
by Guillaume POIRIER 25 Jun '05

25 Jun '05

Hello, Here's a work-in-progress encoding guide for XviD MPEG4-ASP codec that should one day make its way to our documentation. As the world of video encoding is one of those areas where using this or that set of options is often a matter of choice, I'd like to hear what you may have to say about that document. It still lacks some option, and says almost nothing about the PSNR (in/de)crease to expect from using each option. If you have those figures on hand, please feel free to send them to me. It also lack encoding examples, and information about custom quantization matrices, though it seems to me this subject is too controversial to get engraved in stone in an official documentation. All feedbacks are welcome, either technical, or about my louzy English that you wish to improve. Regards, Guillaume ------------------------ <sect1 id="menc-feat-xvid"> <title>Encoding with the <systemitem class="library">XviD</systemitem> codec</title> <para> <systemitem class="library">XviD</systemitem> is a free library for encoding MPEG-4 ASP video streams. Before starting to encode, you need to <link linkend="xvid"> set up <application>MEncoder</application> to support it</link>. </para> <para> This guide mainly aims at featuring the same kind of information as x264's encoding guide. Therefore, please begin by reading <link linkend="menc-feat-x264-intro">the first part</link> of that guide. </para> <sect2 id="menc-feat-xvid-intro"> <title>What options should I use to get the best results?</title> <para> Please begin by reviewing the <systemitem class="library">XviD</systemitem> section of <application>MPlayer</application>'s man page. This section is intended to be a supplement to the man page. </para> <para> The XviD's default settings are already a good trade off speed vs. quality, therefore, if you can safely stick to them if the following section puzzles you. </para> </sect2> <sect2 id="menc-feat-xvid-encoding-options"> <title>Encoding options of <systemitem class="library">XviD</systemitem></title> <itemizedlist> <listitem><para> <emphasis role="bold">vhq</emphasis> Default setting may safely be used on every encode, when higher settings always help quality, but are significantly slower. Turning it off will noticeably speed-up encode if you need speed. </para></listitem> <listitem><para> <emphasis role="bold">bvhq</emphasis> This does the same job as vhq, but does it on B-frames. It has a negligible impact on speed, and slightly improves quality (around +0.1dB PSNR). </para></listitem> <listitem><para> <emphasis role="bold">max_bframes</emphasis> A higher number of consecutive allowed B-frames usually improves compressibility while this may lead to more blocking artifacts. Default setting is a good trade-off of compressability vs. quality, but you may increase it up to 3 if you're bitrate-shorted, while you may also decrease it to 1 or 0 if you're aiming at perfect quality though this might waste more bits than the increased of subjective quality is worth. </para></listitem> <listitem><para> <emphasis role="bold">bf_threshold</emphasis> This controls the B-frame sensibility of the encoder, where a higher value leads to more b-frames being used (and vice versa). This setting is to be used together with <option>max_bframes</option>, so that if you are bitrate-shorted, you should increase both <option>max_bframes</option> and <option>bf_threshold</option>, while you may <option>max_bframes</option> and reduce <option>bf_threshold</option> so that the encoder may use more B-frames in places that only really need them. A low number of <option>max_bframes</option> and a high value of <option>bf_threshold</option> is probably not a wise choice as it will force the encoder to put B-frames in places that would not benefit from them, therefore reducing visual quality. However, if you need to be compatible with standalone players that only supports DivX profiles (which only supports up to 1 consecutive B-frame), this would be you only possibility to increase compressibility through using B-frames. </para></listitem> <listitem><para> <emphasis role="bold">trellis</emphasis> Optimizes the motion estimation and allows significant bit saving which would be spent elsewhere on the video, raising overall visual quality. You can safely leave it on as its impact on quality is very sensible, but if you're looking for speed, only disable it if you have turn down <option>vhq</option> to the minimum. </para></listitem> <listitem><para> <emphasis role="bold">cartoon</emphasis> Designed to better encode cartoon content, and has no impact on speed. </para></listitem> <listitem><para> <emphasis role="bold">me_quality</emphasis> This setting is to control the precision of the motion estimation. The higher <option>me_quality</option>, the more precise the estimation of the original motion will be, and the better the resulting clip will capture the original motion. </para> <para> Default setting is best in pretty much all cases, and it's not recommended to turn it down unless you're really looking for speed, as all the bits saved by a good motion estimation would be spend elsewhere, raising overall quality. Therefore, only go as low as 5, and only as a last resort. </para></listitem> <listitem><para> <emphasis role="bold">chroma_me</emphasis> Improves motion estimation by taking the chroma (the color) information into account, when <option>me_quality</option> alone only uses luma (greyscale). This slows down encoding by 5-10% but improves quite a bit visual quality by reducing blocking effect. If you're looking for speed, you should disable this option before starting to consider reducing <option>me_quality</option>. </para></listitem> </itemizedlist> </sect2> <sect2 id="menc-feat-xvid-example"> <title>Encoding examples</title> </sect2> </sect1> -- A woman isn't complete without a man. But where do you find a man - a real man - these days? -- Lauren Bacall My answer: Only at #mplayerdev on the freenode IRC network.

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What happened to divx?
by Pete Davis 25 Jun '05

25 Jun '05

As per one of the earlier suggestions, I upgraded to pre7 from pre6. Now the same lavc options I was using before for Divx are now giving me a 4CC of FMP4. How do I get it back to doing Divx? Thanks. Pete

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Conversion from avi to mpeg2 summary
by John Dickinson 24 Jun '05

24 Jun '05

I have been working on converting an avi file from a digital camera to mpeg2 (playable by windows media player and others(final target an SVCD)) for the last week and have had help from several people on these lists as well as requests to post the final command line so here it is: mencoder -of mpeg -ovc lavc -lavcopts vcodec=mpeg2video:mbd=2:keyint=25:vrc_minrate=600:vbitrate=2500 -oac lavc -af lavcresample=44100 -srate 44100 -mpegopts format=mpeg2 in.avi -o test.mpg The real trick seemed to be in getting the sound right. Without your help it wouldn't have happened. Even though I constantly refered to the manpages I lacked the technical background for "muxing", resampling, etc. or sufficient knowledge about my taget format and its limitations to know what the error messages meant or why things wouldn't work. Thanks to all who helped again. John

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Getting the sound right in a conversion from avi to mpg (mpeg2)
by John Dickinson 23 Jun '05

23 Jun '05

I am converting an avi file into an mpg file and seem to have gotten the video working well enough (thanks to people here). However the audio is failing for me. The final goal is to have an mpeg2 VCD compatible video file (with audio) for portability to the grandparents old VCD/DVD player. Here is the command: mencoder -of mpeg -ovc lavc -lavcopts vcodec=mpeg2video:mbd=2:keyint= 25:vrc_minrate=600:vbitrate=6000 -vf rotate=1 -oac lavc -af lavcresample=48000:srate=48000 in.avi -o test.mpg Here is the output: MEncoder 1.0pre7-3.4.2 (C) 2000-2005 MPlayer Team CPU: Intel Pentium 4/Xeon/Celeron Foster (Family: 8, Stepping: 7) Detected cache-line size is 64 bytes CPUflags: Type: 8 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 0 SSE2: 0 Compiled with runtime CPU detection - WARNING - this is not optimal! To get best performance, recompile MPlayer with --disable-runtime-cpudetection. File not found: 'frameno.avi' Failed to open frameno.avi success: format: 0 data: 0x0 - 0x289070 AVI file format detected. VIDEO: [MJPG] 640x480 24bpp 30.000 fps 6917.0 kbps (844.4 kbyte/s) [V] filefmt:3 fourcc:0x47504A4D size:640x480 fps:30.00 ftime:=0.0333 ========================================================================== Opening audio decoder: [pcm] Uncompressed PCM audio decoder AUDIO: 16000 Hz, 1 ch, u8, 128.0 kbit/100.00% (ratio: 16000->16000) Selected audio codec: [pcm] afm:pcm (Uncompressed PCM) ========================================================================== PACKET SIZE: 2048 bytes Opening video filter: [expand osd=1] Expand: -1 x -1, -1 ; -1 (-1=autodetect) osd: 1 Opening video filter: [rotate=1] ========================================================================== Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family Selected video codec: [ffmjpeg] vfm:ffmpeg (FFmpeg MJPEG decoder) ========================================================================== [mp2 @ 00A268B8]bitrate 224 is not allowed in mp2 Couldn't open codec mp2, br=224 Seems like the bitrate is the problem but the resample doesn't work. If I get rid of: "-oac lavc -af lavcresample=48000:srate=48000" and replace with "-oac copy" it works but there is no sound with the resultant file. I am really stumped on this even after reading the html version of the manpage that came with the window's binaries of mplayer. John

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Mencoder vs. hardware based devices...
by Brian Keener 23 Jun '05

23 Jun '05

I've achieved fairly consistent and good quality with Mencoder, at this point. My disk space restricts me to capturing at 352x480 or 352x240 (depending on length). I was looking at new hard drives at my local store, and I saw some inexpensive PVR devices (PVR-250 and PVR-150 from Hauppauge), and the thought crossed my mind that they might be adequate for my purposes. Can mencoder give significantly better quality than one of these stand-alone devices? I'm not looking for perfection; I'm only interested in encoding some children's VHS movies, old family videos, etc. Brian K

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Winding (or fast seek, or fast replay)
by oleg dov 23 Jun '05

23 Jun '05

Hi! I don't know how exaclty it's called(sorry for my english), but on my DVD-player some films can be rewinded and some not. So, the question is - what paremeter responds for this functionality and how it's possible to remake films for fast winding with mencoder. Thanks.

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lavc option nr
by Jan Paul Schmidt 23 Jun '05

23 Jun '05

Hi there, does anybody know, how the lavc option nr works? I tried this kind of noise reduction on a cartoon - ripped from a PAL DVD -, but the result is strange. At the GOP boundaries a high quantiziser is used and it looks like the picture have a sort of pump effect. This is not the case when leaving the nr option out. Everything started out with my usual SVCD script, but after trial and error this was left to reproduce this behaviour: mencoder -oac copy -ovc lavc -lavcopts vcodec=mpeg2video:vbitrate=2500:vrc_buf_size=917:keyint=15:nr=400 -o pass1.avi episode1.mpg Note: This is not how I encode SVCDs. This is a very basic command without filters and advanced options, which can reproduce this behaviour. Bringing back the filters and advanced options do not cure the problem. When using . to cycle through the frames the picture at the GOP boundary gets real blocky for one frame and then gets back to normal. I also tested it with MPEG 4: mencoder -oac copy -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=2500:keyint=15:nr=400 -o pass1.avi episode1.mpg but the result suffers from the same problem. The effect can be noticed really good when white text is on a black background. This is a recent cvs checkout of mplayer and lavc. Any ideas? Can someone reproduce this? jps

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Maybe a question for the dvdauthor folks...
by Brian Keener 21 Jun '05

21 Jun '05

An mpeg2 file outputted by the following commandline: mencoder tv.avi -ofps 30000/1001 -of mpeg -mpegopts format=dvd:vbitrate=7000 -oac lavc -ovc lavc -lavcopts vcodec=mpeg2video:vbitrate=7000:keyint=15:vhq -vf hqdn3d,pp=md,scale=720:480,harddup -o tvout2.mpg Gives this result in a very basic dvdauthor test: WARN: Discontinuity in audio channel 8; please remultiplex input. WARN: Previous sector: 3599.416 - 3599.416 WARN: Current sector: 3599.495 - 3599.495 WARN: Discontinuity in audio channel 8; please remultiplex input. WARN: Previous sector: 3599.495 - 3599.495 WARN: Current sector: 3599.573 - 3599.573 WARN: Discontinuity in audio channel 8; please remultiplex input. WARN: Previous sector: 3599.573 - 3599.573 WARN: Current sector: 3599.625 - 3599.625 WARN: Discontinuity in audio channel 8; please remultiplex input. WARN: Previous sector: 3599.625 - 3599.625 WARN: Current sector: 3599.704 - 3599.704 WARN: Discontinuity in audio channel 8; please remultiplex input. WARN: Previous sector: 3599.704 - 3599.704 WARN: Current sector: 3599.782 - 3599.782 WARN: unknown mpeg2 aspect ratio 1 There's literally thousands of those messages in stdout, but the VOB files seem to playback just fine on my desktop PC and on my standalone DVD player. Any hints? Or just send it over to dvdauthor lists? Brian K

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