Michael Rampe
Forum Replies Created
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[David Moises Paz] “It is possible to encode from my camera to the cell’s format so I can watch the videos recorded with the camera in the cellphone? If so, please someone could tell me which are the correct arguments to ffmpeg.”
What you need to replicate is:
Stream #0.0(eng): Video: mpeg4, yuv420p, 176×144 [PAR 1:1 DAR 11:9], 131 kb/s, 11.28 fps, 15 tbr, 15 tbn, 15 tbc
Stream #0.1(eng): Audio: amrnb, 8000 Hz, 1 channels, flt, 12 kb/sFor the video:
ffmpeg -i inputfile.mov -b 131k -r 15 -s 176×144 output.mp4Not too sure about the audio as I haven’t used “amrnb” before. From what I have read, you might need to install the amr libraries and reconfigure and make FFmpeg with this codec enabled.
Michael
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[Veeru Muvva] “I am trying specific GOP in h264 to decode and re encode. But I can’t able to see any video of that GOP but I can able to hear Audio only.”
Can you post your command lines?
Michael
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[Qiang Wang] “Obviously the video and audio lengths are different. My question is how can I make them synchronized. I hope I can do that without recoding the video stream.”
Have a look into the -async option.
Michael
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[Lossius Thomas] “It’s been three days (much more actually) that I have problems with FFmpeg, my goal is to install FFMPEG + x264 + AAC + libavfilter.”
Not sure about your issues… but:
Do you really need the SOC libavfilter? A lot of the SOC filters are now present in the trunk and unless there is something specific you need in libavfilter, I would recommend the FFmpeg SVN trunk rather than the version that SOC libavfilter needs/gets.
Michael
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[Dmitry Kaflik] “The problem is that if i try to extract frame from the end of file its take a lot of time and i need to get about 100-1000 frames from video file. If i run ffmpeg 100-1000 times its every time going to parse video from the begining to reach pointed time (for example -ss 00:00:45).”
It is all about where you put the -ss flag.
If you put it after the input, FFmpeg reads every frame up until the one you need. (as in your example) AFAIK, this is required if the frame you want to export is not an I frame.
If you put it before the input, such as:
ffmpeg -y -ss 00:00:45 -i akisora.mp4 -an -r 1 -f mjpeg -vcodec mjpeg -vframes 1 “test.jpg”
FFmpeg will only read the frame you specified and thus do the output almost instantly. Unfortunately, you will lose accuracy with this method because for me it only exports the closest I frame. (I have also read reports that for some other users, this method will produce a grey output frame if it is on a P or a B frame.)
[Dmitry Kaflik] “So my question: is there any way to point ffmpeg to the list of frames that i need to extract, so it cat do extraction in one-pass?”
One way which would be fast and accurate, if you are exporting 1000 stills, is simply export the whole movie to stills and keep the ones you need. A simple shell script should be able to achieve this. This way, FFmpeg will only read through the file once and you can delete the unnecessary ones.
Michael
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[Erik Freid] “Real time encoding (or even faster than real time) is possible with enough horsepower and memory.”
I agree with this in terms of full broadcast size and framerate but *most* machines are capable of real-time encoding at some level. You need to restrict the size of the video to a level where your machine can keep up with the input. This may be very small for slower machines.
Another way, if using x264, is to limit the toolset it uses to encode. There are many presets for x264 and quite a lot of them work in faster than realtime for me at 720p. Of course, all of this is usually at the expense of quality.
This reminds me of the old saying: Fast, good and cheap, you can only pick 2.
Michael
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[Seb Ar] “The part and duration of that new video are correct, but the video is upside down.”
I have seen this symptom posted in several places but alas, could not find a solution or cause. I cannot replicate the problem.
It would be a good idea to try to see if the cause is AVI files in general or an encoder bug. Does it happen if you use a different input format like mp4?
Michael
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Not sure. Works for me in Australia….
might be an issue specific to the UK.
Maybe try to install the hard way using SVN and compiling the required libraries yourself. Quite a bit trickier than Macports but you do get the latest stable development version that way.
Michael
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[Mahesh Kumar] ” While converting other format videos to flv, it is not working. But flv to flv is working.”
Please post command line and error messages.
Michael
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[Tom Arik] “I’m trying to use ffmpeg.exe in order to…”
Can you post an example of what you have been trying and the errors you are receiving?
[Tom Arik] “…with no transcoding AT ALL”
-vcodec copy
Michael