I'm converting .flac and .mp3 audio files to .m4a using ffmpeg with libfdk_aac (Fraunhofer AAC encoder) like this:
ffmpeg -i "001.flac" -c:a libfdk_aac "001.m4a"
This works fine, but in case of .flac the resulting .m4a files include ~0.046 seconds of silence at the start and sometimes a few extra milliseconds at the end. Though, I need the .m4a files to be of exactly(!) the same length without any extra silence. Is there a way to achieve this?
EDIT: At the moment I'm using an additional step, i.e. cutting the resulting .m4a file works at least in the beginning of the track, but there are still some (varying) extra ms in the end:
ffmpeg -i 001.m4a -ss 0.047 -c:a libfdk_aac 001cut.m4a
No, it’s not possible. The different codecs use different frame sizes.
Related
I use this command to crop a few seconds of mkv/mp4 videos. Sometimes it works perfectly fine.
But other times the output file which is in mp4 format only contains the audio. How can I fix it?
ffmpeg -i input.mp4 -ss 01:10:15 -to 01:10:20 -c:v copy -c:a copy output.mp4
Don't use -c:v copy -c:a copy Re-encode it.
Direct stream copy copies the GOP (Group of pictures) chunks of the structure of file (from the first I-frame to the last P or B-frame).
Presumably your time is too short, less than one chunk of GOP.
I've been looking all over the web & StackOverflow, and can't get this to work. I have an audio file that I'd like to split into mp3 files and generate a corresponding m3u8 file.
I've tried this, which was the closest:
ffmpeg -i sometrack.wav -c:a libmp3lame -b:a 256k -map 0:0 -f segment -segment_time 10 -segment_list outputlist.m3u8 -segment_format mpegts 'output%03d.mp3'
But all the mp3 files are garbled when I play them.
There are two issues here. FFmpeg normally looks at the extension of the output files to determine output container. However, when the output format is forced -segment_format for segment muxer or just -f format for most others, ffmpeg will pay heed to that and no longer look at the extension. In this case, segment_format is set to mpegts so that's what the output files will be. To ensure valid mp3 files, set segment_format to mp3.
The second issue is that since the extension is mp3, my guess is that hls.js is not able to correctly determine the format of the segments, or it assumes a wrong format and tries to parse them that way. Either way, there should be some messages in the browser console to that effect. See https://github.com/video-dev/hls.js/pull/1190 for issues that hls.js has had with format probing.
I have learned through Google, that to change video containers without losing quality I can run the following command:
ffmpeg -i videofile.mkv -codec copy videofile.mp4
This has worked great for a number of video files I have. However, I am having an issue with three of them (1 mkv file and 2 avi files). When I run that command against them, the video is there, but there is no sound. There is sound in the original video file.
Any ideas how to put the video in a new container while retaining the audio track?
Thanks. Brian
The .mp4 container is not compatible with the audio codecs of the problem files. This should be evident from the logs. So the audio channels of the problem files have to be transcoded to something allowed in .mp4, eg. aac:
ffmpeg -i videofile.mkv -c:v copy -c:a aac videofile.mp4
Maybe the container mp4 it doesn’t compatible whith codec of your input video mkv and avi
By the way, you can try
ffmpeg -i videofile.mkv -c:v copy -c:a copy videofile.mp4
Check this documentation.
https://en.m.wikipedia.org/wiki/Comparison_of_video_codecs
https://trac.ffmpeg.org/wiki/Map
i try to write an .sh that read a folder create a playlist of mp4 files and then generate an only big video with a sequence of all videos find in the folder, and encode it for dash:
printf "file '%s'\n" ./*.mp4 > playlist.sh
ffmpeg -f concat -safe 0 -i playlist.sh -c copy concat.mp4
Till now i follow the demux concat official guido to ffmpeg website.
Without result, also the following give me "more than 1000 frames duplicated between videos of the sequence"
ffmpeg -f concat -i playlist.sh -c:a aac -b:a 384k -ar 48000 -ac 2 -c:v libx264 -x264opts 'keyint=50:min-keyint=50:no-scenecut' -r 25 -b:v 2400k -maxrate 2400k -bufsize 1200k -vf "scale=-1:432 " out.mp4
Thanks a lot
Sry, cannot comment (yet)...
Your commands are correct, I could just concat some sample videos.
Do you always get the mentioned error, or also something else? And is the video working, or no video is created?
In most cases, the input video is incorrect. Wrong input format (not fitting to file extension) or worse like ending at wrong frame.
Perhaps you can make the video available?
PS: Needed to add -safe 0 to the second command to avoid error [concat # 0x7fbfd1000000] Unsafe file name './small.mp4'
Hint: Do not use file extension .sh for your list of video files. This extension is used for shell scripts, so it can be confusing. Just use .txt.
UPDATE #Massimo Vantaggio
We should not create new answers, but I cannot comment yours and I also don't know how to continue our discussion, so I edit my answer.
Your videos don't look very different. Can't see, what's wrong with the first one.
Perhaps you could use ffprobe -report input.mp4 to get more informations. Look for errors or warnings.
My assumption is still that the video was cut in a hard way (by conversion software), so keyframes are messed up or something else.
You can also try to first reencode your video with ffmpeg. After that, it should be complete compatible with ffmpeg ;)
Something like this:
ffmpeg -i small.mp4 -acodec aac -ab 192k -vcodec libx264 -vb 1024k -f mp4 output.mp4
Use -ab and -vb from your input video, or at least the bitrate from input. Quality will decrease a little bit and file size increase, but it should be okay.
We're converting a bunch of .RM files to .MP4 and wondered what the best way is. Here are the details:
Convert the files to H.264.
Keep the filename but add .mp4 to the end.
Also extract a JPG image of the video at about 5 seconds in for each file and name it the original filename + .jpg.
This is on a Windows system. Is there a free tool you recommend for this? Thank you.
ffmpeg is pretty much the defacto standard app for transcoding video.
http://www.ffmpeg.org/
Convert to h264/mp4:
ffmpeg.exe -i inputFile.rm -vcodec libx264 -s 320x240 -acodec libfaac outputFile.mp4