June 2005 - ffmpeg-user - lists.ffmpeg.org

Cropping
by evert＠collab.nl 19 Jun '05

19 Jun '05

Hi, I have an FFMpeg script running on a server and some users send in video's with weird sizes. I would like to be able to automaticly crop images when it isn't 4:3, because I don't want to stretch them. How would I do this using ffmpeg? Would I have to use the library to first return the original width and height to do the calculations myself? regards, Evert

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Streaming with seek
by andyparkins＠gmail.com 17 Jun '05

17 Jun '05

Hello, I'm using ffmpeg to record a live MPEG4 stream. This is working well. However, when I try to play back the stream - with say ffplay - I can't seek properly. The problem, I believe, is that the file is still open and so hasn't has whatever headers/trailers that are needed written to it yet. My question then is what output format should I be using? I'd like to be able to view the stream "live" but still seek backwards in time. A bit like a TiVo or similar. Andy -- Dr Andrew Parkins, M Eng (hons), AMIEE

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buffer underflow woes
by list1＠michaelshell.org 16 Jun '05

16 Jun '05

Hello, I am using ffmpeg (20050612 snapshot) on my 2.6.8.1 K6-2 Linux box. When running ffmpeg on a vob file (from a DVD) like this: ffmpeg -i in.vob -f avi -hq -sameq -aspect 4:3 -vcodec mpeg2video -ac 2 -acodec mp2 -target dvd -y out.avi (the file is 283MB - much too large for me to upload or email) about 5 minutes into the conversion I get warnings like: [dvd @ 0x400778a8]buffer underflow [mpeg2video @ 0x40337750]rc buffer underflow bitrate=5984.4kbits/s I understand in general what a buffer underflow is, but not specifically as to what buffer within ffmpeg (and what sizes, fills and empties it). 1. What conversion buffer is underflowing? - can someone explain a little about the nature of this in ffmpeg? 2. What command line options can I use to prevent it? 3. Is the output noticeably affected by underflows? Thanks in advance, Mike Shell

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not encoding properly on 2,4,8,16 fps
by manishpa＠motechsoftware.com 16 Jun '05

16 Jun '05

Hi, I am capturing video from a live source and encoding in mp4 file format by using ffmpeg 0.4.9-pre1 There is some problem with ffmpeg mpeg4 codec. At 4, 8 and 16 fps the ffmpeg mpeg4 codec is not working properly. The captured mp4 file can not be played on QuickTime. I tried ffmpeg (mpeg4) for capturing from video source. At 4, 8 and 16 fps the mp4 and 3gp files generated by ffmpeg (mpeg4) can not be decoded correctly in Quicktime. If I use avi file format for output, the file can be played by any media player. Is anyone aware of this issue? If anyone knows some workaround, please do let us know. It's urgent. Regards, Manish ------------------------------------------------------------------------------------------------------------------------------- DISCLAIMER: This message (Including any attachments) is confidential and is intended only for the addressee. All MoTech Software mails and attachments are scanned for all known viruses at the time of transmission. However, please scan the mail and attachments for viruses before opening or downloading from this transmission. We will not accept any liability for damages through virus. If you are not the intended recipient or received this message by mistake, please notify the sender by E-mail & delete the message from the system. Any unauthorized use or dissemination of the message in whole or part is strictly prohibited.

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by 527field＠accesscable.net 16 Jun '05

16 Jun '05

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grap two video tracks into one quicktime file
by tps＠netmaster.dk 16 Jun '05

16 Jun '05

Hi all I have two cameras on the same event. The event is a ball game. I want to grab from my camcorder(ieee1394) and my webcam (v4l). Is there any way I can use ffmpeg to grap both video tracks into one quicktime file? I guess I have to grap the two video tracs into two tracks of the same quicktime file in order to keep the two tracks in sync - correct ? Any help is appreciated! Thanks

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Q-value not being displayed in ffmpeg?
by boehme＠inb.uni-luebeck.de 14 Jun '05

14 Jun '05

Recently, while encoding a video with ffmpeg, I noticed that the Q-value wasn't being displayed correctly -- it was a constant "0.0". This was with the latest CVS version, while encoding an MPEG-1, -2 or -4 video with constant bitrate (haven't tried it with other codecs yet). The effect did not seem to depend on the input file, but I can provide a sample if desired. One command line that shows the effect is ffmpeg -i ~/tmp/test.mpg ~/tmp/test2.mpg but the effect does not seem to depend on the parameters. The output for the above command line is ffmpeg version 0.4.9-pre1, build 4756, Copyright (c) 2000-2004 Fabrice Bellard configuration: --prefix=/data/boehme/mylibs built on Jun 14 2005 09:38:59, gcc: 3.3.4 (pre 3.3.5 20040809) Input #0, mpeg, from '/nfshome/boehme/tmp/test.mpg': Duration: 00:01:11.0, start: 0.500000, bitrate: 324 kb/s Stream #0.0[0x1e0]: Video: mpeg1video, yuv420p, 320x240, 29.97 fps, 104857 kb/s Stream #0.1[0x1c0]: Audio: mp2, 44100 Hz, stereo, 64 kb/s Output #0, mpeg, to '/nfshome/boehme/tmp/test2.mpg': Stream #0.0: Video: mpeg1video, yuv420p, 320x240, 29.97 fps, q=2-31, 200 kb/s Stream #0.1: Audio: mp2, 44100 Hz, stereo, 64 kb/s Stream mapping: Stream #0.0 -> #0.0 Stream #0.1 -> #0.1 Press [q] to stop encoding frame= 2403 q=0.0 Lsize= 2810kB time=80.1 bitrate= 287.2kbits/s video:2150kB audio:626kB global headers:0kB muxing overhead 1.229093% Martin -- Martin B?hme Inst. f. Neuro- and Bioinformatics Ratzeburger Allee 160, D-23538 Luebeck Phone: +49 451 500 5514 Fax: +49 451 500 5502 boehme at inb.uni-luebeck.de

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feeding ffmpeg on the fly
by manzato81＠yahoo.com.br 13 Jun '05

13 Jun '05

Hi, I want to know if it is possible to feed a ffmpeg conversion at the time a file is being created by another program. I mean, I'm working with mp4live, which is capturing and recording a mp4 video to a shared folder hosted by another computer. At the same time, I want to start ffmpeg at this computer to do some conversions (such as size, bitrate and framerate adaptations). These conversions must be done in real time, because the file(s) generated by ffmpeg will be live-accessed by clients (using Darwin Streaming Server which accesses these files by previously generated sdp files). My goal is to create a live content-based adaptation mechanism so that clients with less process power can access video without any problem. Because of this, the parameters of the conversion will be passed to ffmpeg as soon as the client requests for some video with a specific configuration (so, I cannot specify staticaly a set of configurations to be generated by ffmpeg, it will have to be done on the fly) I have tried once using raw data produced by mp4live, I started the capturing and recording job, and then, I started the ffmpeg conversion. But I realized that ffmpeg seems to be faster then the broadcaster, so it finishes the conversion without waiting for more data. Is there a better way to do that without changing the source code of ffmpeg? Any ideas will be apreciated. Thanks very much. Manzato __________________________________________________ Converse com seus amigos em tempo real com o Yahoo! Messenger http://br.download.yahoo.com/messenger/

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timestamp to frame
by kryptolus＠gmail.com 12 Jun '05

12 Jun '05

I was wondering if there was a different way that I could seek in a video file. something that is more "virtual dub compatible". Right now I go to the nearest keyframe, and then keep reading frames until the frame's pts is equal to or before the target time. It works well, but I end up being off by one or two frames from the frame that Virtual Dub would show for that time. Judging from the code, Virtual Dub calculates the frame by multiplying the frame rate by the target time and then seeking to that frame. Is there any way I could accomplish something similiar using ffmpeg?

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ffmpeg crop woes
by list1＠michaelshell.org 12 Jun '05

12 Jun '05

Greetings, First of all, a big thank you to all the ffmpeg developers - I sure hope that we can keep such a useful library/utility going. I recently installed FFMpeg-20050612 on my 2.6.8.1 kernel, gcc 3.4.2, K6-2 linux machine. I configured ffmpeg with: ./configure --prefix=/usr/local --enable-mp3lame --enable-libogg --enable-vorbis --enable-shared I did get a compile error: gcc -O3 -g -Wall -Wno-switch -I.. -I'/home/mshell/DLOADS2/UPZ/FFMpeg-20050612' -I'/home/mshell/DLOADS2/UPZ/FFMpeg-20050612'/libavcodec -DHAVE_AV_CONFIG_H -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_GNU_SOURCE -c -o grab.o grab.c In file included from /usr/include/linux/videodev.h:8, from grab.c:26: /usr/include/linux/videodev2.h:436: error: parse error before '*' token which was resolved following the advice of http://www.linuxtv.org/mailinglists/vdr/2004/07-2004/msg00510.html where it says to add -D__user= to CFLAGS=$ line in /libavformat/Makefile I did this and got a good compile. OK, ffmpeg seems to work now, except for cropping. I have a 352x240 .avi file with mpeg 2 video and mpeg layer 2 audio. I want to crop a tad off the bottom and right (and then resize back to 352x240). If I try something like: ffmpeg -ac 2 -r 29.971 -b 614.6 -cropbottom 16 -cropright 16 -s 352x240 -i in.avi -f avi -vcodec mpeg2video -acodec mp2 -y out.avi (BTW, I am using the correct frame rate if I ultimately want to create a DVD, and will "-target dvd" take care of this?) I get: "Vertical crop dimensions are outside the range of the original image. Remember to crop first and scale second." which is not so helpful IMHO. I read: http://www.videohelp.com/forum/archive/t238937.html But, I still don't get if I am doing something wrong. Can anybody with a recent ffmpeg please check that cropping (still) works and if so, provide me some valid values to get started with? Any help or suggestions would be much appreciated. Thanks in advance, Mike Shell

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