I'm having an issue where I'm trying to concat 4 audio files into one file, I want them to not play on each other, only after each other. I was wondering if this was possible.
I have it working somewhat right now, however, the final result is weird, the first, second, and 4th ones sound okay, but the 3rd one, the longest in my case, is sped up like a chipmunk.
Here is the command I typed
ffmpeg -f concat -i mylist.txt -c copy output.wav
And here is the mylist.txt:
file 'Alert.wav' file 'Attention.wav' file 'voice.wav' file 'Clear.wav'
I am trying to get the results to be the same length, and the same quality as their source files. Just, connected in one file, kind of like if you open a video editor and attach them into one, but that in my case will not work because I need it to be automated.
Related
I am making a datamoshing program in C++, and I need to find a way to remove one frame from a video (specifically, the p-frame right after a sequence jump) without re-encoding the video. I am currently using h.264 but would like to be able to do this with VP9 and AV1 as well.
I have one way of going about it, but it doesn't work for one frustrating reason (mentioned later). I can turn the original video into two intermediate videos - one with just the i-frame before the sequence jump, and one with the p-frame that was two frames later. I then create a concat.txt file with the following contents:
file video.mkv
file video1.mkv
And run ffmpeg -y -f concat -i concat.txt -c copy output.mp4. This produces the expected output, although is of course not as efficient as I would like since it requires creating intermediate files and reading the .txt file from disk (performance is very important in this project).
But worse yet, I couldn't generate the intermediate videos with ffmpeg, I had to use avidemux. I tried all sorts of variations on ffmpeg -y -ss 00:00:00 -i video.mp4 -t 0.04 -codec copy video.mkv, but that command seems to really bug out with videos of length 1-2 frames - while it works for longer videos no problem. My best guess is that there is some internal checker to ensure the output video is not corrupt (which, unfortunately, is exactly what I want it to be!).
Maybe there's a way to do it this way that gets around that problem, or better yet, a more elegant solution to the problem in the first place.
Thanks!
If you know the PTS or data offset or packet index of the target frame, then you can use the noise bitstream filter. This is codec-agnostic.
ffmpeg -copyts -i input -c copy -enc_time_base -1 -bsf:v:0 noise=drop=eq(pos\,11291) out
This will drop the packet from the first video stream stored at offset 11291 in the input file. See other available variables at http://www.ffmpeg.org/ffmpeg-bitstream-filters.html#noise
I understand how to make timelapse video from the sequence of files.
But what if my files have names like YYYYMMDDHHmmSS.jpg? How can I pass them in the correct order? I would prefer not to rename them (there are 55'000 files, almost 10 Gb).
I just found that there is no much sense to do any additional actions, the files are already sorted in the correct order, so the command below works well:
ffmpeg -framerate 500 -pattern_type glob -i '*.jpg' -c:v libx264 -pix_fmt yuv420p out2.mp4
I know there are some bat/shell commands possible for that, but IMHO it makes things more complicated for so little.
In similar cases I prefer using renaming softwares like Ant Renamer.
Drag & drop your files in the main window
In the Actions tab, click Enumeration in the list
You're given a naming scheme (look down the options to see the different schemes available).
I recommend using the default %name%_%num%%ext%, starting at 1 and with one more digit than your total number of files. Which in your case will result in YYYYMMDDHHmmSS_XXX.jpg
Click the Go button to process.
Once finished, check if the numbers added adequate the original file names (it should since the naming used is already chronological, but do check for safety).
It might not suit you, especially if you really want to do everything from command lines. But for other people, it might be enough.
Say we have many video records that we want merge with -vcodec copy (or equivalent syntax). Without reencoding, without loss of quality. And few records (minor set), with another codecs, parameters and so on. So we can use ffprobe for file, that represent majority of sources. We get lot of information.
But can we get here commandline hints for ffmpeg, that could be used to convert another (not yet "compatible") files to this same format? At least for one selected stream of "master" file, for example.
Question is not about some scpecific output codec and so on.
There is no exsitsing tool to to this. You would need to write one.
Each video stream inside a video file can only include same codec. So I recommend you to at first step, merge files with same codec with -vcodec copy. The check if which codec is mostly available in your merged files (e.g. CodecA). At second step, convert other merged files with other codecs to CodecA. Finally, merge all files (which all have now CodecA) with -vcodec copy.
Please keep in mind that if the video files are in different sizes, you have to reencode them.
I'm developing a system using ffmpeg to store some ip camera videos.
i'm using the segmentation command for store each 5 minutes a video for camera.
I have a wpf view where i can search historycal videos by dates. In this case i use the ffmpeg command concat to generate a video with the desire duration.
All this work excelent, my question is: it's possible concatenate the current file of the segmentation? i need for example, make a serch from the X date to the current time, but the last file is not generated yet by the ffmpeg. when i concatenate the files, the last one is not showing because is not finish the segment.
I hope someone can give me some guidance on what I can do.
Some video formats can always be playable during the build process. That is, you can make a copy of the unfinished segmentation directly and use it to merge.
I suggest you use flv or ts format to do this. mp4 is not supported. Also note that there is a delay from encoding to actually writing to the disk.
I'm not sure if direct copy will cause some data problems at the end of the segmentation file, but ffmpeg will ignore this part of the data during the merge process, so the merged video should be fine.
how can i create a checksum of only the media data without the metadata to get a stable identification for a media file. preferably an cross platform approach with a library that has support for many formats. e.g. vlc, ffmpeg or mplayer.
(media files should be audio and video in common formats, images would be nice to have too)
Well, it may be 11 years too late for an answer, but in case others like me stumble upon this...
ffmpeg can output checksums for individual streams. So the same audio or video would output the same checksum independently of it's container format or metadata.
Example for the video track of file $filename, writing the output to $filename.md5 :
ffmpeg -i "$filename" -map 0:v -codec copy -f md5 "$filename.md5"
For audio, use -map 0:a.
To output to STDOUT, use -. For example:
ffmpeg -i "$filename" -map 0:a -codec copy -hide_banner -loglevel warning -f md5 -
I don't know of any existing platform-independent software that will accomplish this, but I do know a way that this could be accomplished in an interpreted (platform-independent) language such as Java.
Essentially, we simply need to strip any metadata (tags) from the file, demultiplexing video files beforehand. Theoretically after demux and removing metadata, one could hash the file and compare against another file that has undergone the same process to match identical files despite having different tags. Unlike a fingerprint, this would not identify similar songs/movies but identical files (imagine you might want the 10 different versions or bitrates of a given song you've archived, but don't want 2 identical copies of any of them floating around).
The most troubling part of this is removing tags as there are many different specifications for tag formats which are not necessarily implemented the same across different applications, i.e. the same exact audio file given identical tags separately through two different applications may not result in identical output files. The only way this could pose an issue fatal to the concept of an audio-only checksum is if popular tagging software makes any changes to the binary audio portion of the file, or pads the audio in a non-standard way.
Taking a checksum is trivial, but I'm not aware off the top of my head of any platform independent libraries to demux and detag mpeg files. I know that in 'nix environments, mpgtx is a great command-line tool that could perform the demux and detag, but obviously that is not a platform-independent solution.
Maybe someone out there feels ambitious?
one possible solution i found seems to be with vlc:
./VLC -I rc snd.mp3 :sout='#std{mux=raw,access=file,dst=-}' vlc://quit | sha1sum