Extract clip from video ffmpeg
17.07.2020 | by Gokree
I'd like to extract from it about 40 clips, of varying lengths. I know the "start" and "stop" time for each. It might look like this:.
I can certainly write a script to extract each of these individually via something like what's described herebut that requires "reading through" the source forty times, which can be slow. Is there a way to get ffmpeg to do this in some sort of sequential fashion in a single pass? Or do I just resign myself to an overnight background process? According to Gyan, the referenced command does an efficient job, and won't read through MP4s but use an index to jump to the inpoint.
So there's no real need to optimize. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Efficiently Extract multiple clips from a long video, possibly with ffmpeg Ask Question.
Asked 1 year, 1 month ago. Active 11 months ago. Viewed times. John John 2 2 bronze badges. The referenced command does an efficient job, and won't read through MP4s but use an index to jump to the inpoint.
In my experience, using -ss, even with the newest versions of ffmpeg, does not give perfect frame accuracy. If you use "-vcodec copy", as in the link you suggested, you'll get cuts on keyframes, which can be a number of frames away from the frame you actually want to cut on. Even if you re-encode, though, you'll often get off-by-one errors, presumably from floating point division mismatches. Let's say you want to start at frame 23 of a Since -ss doesn't allow frame numbers, you'll have to specify something like "-ss 0.
Video Production Stack Exchange is a question and answer site for engineers, producers, editors, and enthusiasts spanning the fields of video, and media creation. It only takes a minute to sign up. A client wants me to write some software, perhaps ffmpeg wrapped in scripting, which will monitor a streaming video feed, and copy clips from it in near real-time, delivering them as self-contained video files.
It is not acceptable for me to wait for the feed to finish, and the video to be completely stored as a local file, before I copy the clips. On the other hand, I can take say tens of seconds after the end time of the clip before delivering it. Can I do this without building a video processing suite from scratch? Do I need to require that the streaming video feed be a certain format?
So say the video feed is of a 1-hour live event. At some point, maybe 5 minutes in, my software may get the command, "clip from 4 minutes 30 seconds to 6 minutes 0 seconds, save as file X. I have to tap into the video feed, copy 90 seconds of video, and store it as file X. The actual times are more flexible, I just want to emphasise that I must be able to tap into the streaming feed in progress, I can't wait for a static video file.
I don't even know if streaming video formats permit this kind of operation. If a receiver writes the feed to disc, will the beginning of the file be legal syntax which a normal tool like ffmpeg can parse?
Is it important to know when the key frames are added? Can normal tools parse video past the most recent key frame to the frame just being written, or would the data in the stored file be still be in some temporary state, and thus not yet parseable?Extracting Still Images from Video with FFMPEG
Or, is copying video clips from streaming video a difficult task which requires more sophisticated software than ffmpeg or the like, wrapped with scripts? Ideally, the stream should be past or close to it when you run the latter command.
Note that since the 2nd command doesn't transcode, inpoint seek isn't precise. The extract will start from the nearest keyframe earlier to the specified inpoint. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. How can I extract clips from a streaming video feed in near real-time?
Ask Question. Asked 2 years ago. Active 1 year, 10 months ago. Viewed times. Advice on specific formats, and tool chains which make this possible are welcome. Active Oldest Votes. Jim DeLaHunt 4 4 bronze badges. Gyan Gyan Sign up or log in Sign up using Google.Every video or animation you see on your television, computer, phone, tablet or even at the movie theater is made up from a succession of still images. These images are then played one after the other several times a second which fools your eye into thinking the object is moving.
The quicker the images are played, the smoother and more fluid the movement looks. Most movies and TV programs are filmed at around images per second, each individual image is called a frame which is where you see the term frames per second FPS.
A video file on a computer simply stores all the frames together and plays them in order, and the total frames stored for a typical movie reaches into the hundreds of thousands.
If you want to extract a succession or range of frames or even all frames from a short video clipcapturing the images one at a time is incredibly inefficient and time consuming.
For that purpose, you need a program that can extract however many video frames you want and save them to image files automatically, like jpg or png.
Here are 5 ways to do it. The program itself will save frames from a video file to a sequence of JPG images. There are four extraction methods to choose from, extract an image every number of frames, extract an image every number of seconds, take a total number of frames from the video or extract every single frame. Set your extract criteria and optionally a different save location to the default, then start the process.
Extraction times are reasonable and will differ depending on video length and how many frames are being extracted. There are a few issues with one or two of the preset values or if you enter a custom value in the frame boxes. That could change to anything else at any time though so you just need to pay attention during setup.
VLC is a popular open source media player that can save sequences of images from any video you choose to play. This can be achieved through the main user interface while more advanced users can use Command Prompt. The ratio will save an image every xx number of frames, so if your video is 30 frames per second, a value of will save an image every 5 seconds. Using multiples of that value will give you a recording ratio in seconds.
Play the video file and the images will automatically start saving. They will continue to save until you press stop, even if you pause or skip through the video. For some reason more recent versions of VLC do not recognize the scene filter is enabled until you close and re-open the program. Once you are done saving frames the option needs to be turned off again or it will do the same with every video you play.
Follow steps 1 and 3 above then untick the Scene video filter box. The biggest drawback with VLC is that you have to leave the video running while taking the images, for this reason we recommend VLC for shorter clips only unless you plan to watch the video anyway.
Open a Command Prompt and change the directory to where vlc. Pathtovideo is the name and path of the video file, --scene-path is the target folder for the images while --scene-ratio is the frame save interval.
An advantage over the GUI method is the ability to use --start-time and --stop-time to start and stop saving frames at specific times in seconds. Leave those switches out if you want to play the whole video. Refer to the complete list of commands at the Videolan website. VLC will run and start the playback but without the screen. Once finished, it will automatically exit. Extract both zip archives. Run Virtualdub. If you wish to save every frame of a small video file to images, skip to step 5.
The No change option at the top will tell you how many frames per second the current video uses. Click OK. Then click OK and VirtualDub will begin to process the video. An additional option in VirtualDub is setting a specific range inside the video itself so only images between the two points are saved.
Before saving at step 5, use the slider and frame controls to set the start range and press the Home key or selection start button in the red box abovemove the slider to the end of the range and press the selection end button or the End key. Now when you save the images, only the selected frames will be saved between the start and end selection points.Convert WAV to MP3, mix down to mono use 1 audio channelset bit rate to 64 kbps and sample rate to Hz: ffmpeg -i input.
Picking the 30 seconds fragment at an offset of 1 minute: In seconds ffmpeg -i input. Split an audio stream at specified segment rate e. The -i option in the above command is simple: it is the path to the input file.
The second option -f mp3 tells ffmpeg that the ouput is in mp3 format.
Cutting Videos with FFmpeg
The third option i. The last param is the name of the output file. You say you want to "extract audio from them mp3 or ogg ". But what if the audio in the mp4 file is not one of those? So why not leave the audio format detection up to ffmpeg? You can of course select any ffmpeg parameters for audio encoding that you like, to set things like bitrate and so on.
Use -acodec libmp3lame and change the extension from. If what you want is to really extract the audio, you can simply "copy" the audio track to a file using -acodec copy. Of course, the main difference is that transcoding is slow and cpu-intensive, while copying is really quick as you're just moving bytes from one file to another. Here's how to copy just the audio track assuming it's in mp3 format :. Note that in this case, the audiofile format has to be consistent with what the container has i.
You can use the ffprobe command to see which formats you have, this may provide some information:. A possible way to automatically parse the audio codec and name the audio file accordingly would be:. Note that this command uses sed to parse output from ffprobe for each file, it assumes a 3-letter audio codec name e.
You can modify a video file directly without having to re-encode the video stream. However the audio stream will have to be re-encoded. Left channel to mono: ffmpeg -i video. Here's a command line that will slice to 30 seconds without transcoding: ffmpeg -t 30 -i inputfile. Do you need to cut video with re-encoding or without re-encoding mode? You can try to following below command. Example: ffmpeg -i source. Example: ffmpeg -i input.
Very little change in video quality. Example: ffmpeg -i video. You're missing command lines from copying audio streams to other containers without re-encoding, which are among the most useful commands because you have no quality loss and can make a stream compatible with different devices! It's all in ffmpeg home page!
Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I tried to cut the video using the start and end time of the video by using the following command.
By using the above command i want to cut the video from to But it is not cutting the video between those times instead of that it is cutting the video with first 11 seconds. I have tried to cut by using the following command which is suggested by mark4o.
You probably do not have a keyframe at the 3 second mark. Because non-keyframes encode differences from other frames, they require all of the data starting with the previous keyframe.
With the mp4 container it is possible to cut at a non-keyframe without re-encoding using an edit list. In other words, if the closest keyframe before 3s is at 0s then it will copy the video starting at 0s and use an edit list to tell the player to start playing 3 seconds in. If you are using the latest ffmpeg from git master it will do this using an edit list when invoked using the command that you provided. If this is not working for you then you are probably either using an older version of ffmpeg, or your player does not support edit lists.
Some players will ignore the edit list and always play all of the media in the file from beginning to end. If you want to cut precisely starting at a non-keyframe and want it to play starting at the desired point on a player that does not support edit lists, or want to ensure that the cut portion is not actually in the output file for example if it contains confidential informationthen you can do that by re-encoding so that there will be a keyframe precisely at the desired start time.
Re-encoding is the default if you do not specify copy. For example:. When re-encoding you may also wish to include additional quality-related options or a particular AAC encoder. Also, the -t option specifies a duration, not an end time. The above command will encode 8s of video starting at 3s.Update : Still using this 8 years later, but in the form of a quick scriptwhich is useful if you are doing it more than once.
Edit: Thanks to DieBagger who pointed out it is much faster to place the seek argument before the input file, and Matthias his point about the seek time.
Glasgow University graduate. I have wide-ranging interests - please see my about page either here or at roberthallam. Hey DieBagger, thanks for the tip, I will test and confirm that! Why does the order of the arguments matter in this case, can you say? It would be good to know exactly why it works this way though.
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Putting the -ss before the -i is faster and less precise because ffmpeg does not decode the video to find the frame.
I think this has something to do with keyframes. Because of this I have found it to be problematic with some videos that will produce a gray frame, whereas putting the -ss after the -i will work fine though of course much slower.
Thanks Rob! You can use -ss both before and after the -i.
The -ss before will skip to the nearest keyframe before the specified time. What you can do and possibly use a simple wrapper script to generate this is. Quite possibly adding -ss 0 after the -i file. Certainly if I extract a 10 second segment using. Matthias: True- you can specify the time in either hh:mm:ss. I will update the post to point this out. Close Menu About. Update : Still using this 8 years later, but in the form of a quick scriptwhich is useful if you are doing it more than once Dead handy, this: ffmpeg -ss 0.
ZZZZ sexagesimal format -s x : frame size of image to output image resized to fit dimensions -f image2 : forces format I use this to generate preview stills for jwplayer to use.
Dead handy! Tags ffmpegimagelinuxvideo. Thx man, one suggestion though: if you put the -ss in front of -i, ffmpeg will seek to the given position much faster…. Yes, -vframes 1 did the trick for me.
Certainly if I extract a 10 second segment using ffmpeg -ss -i file. Excellent Post, thanks for sharing.
Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I'm trying to extract the video stream from an mp4 or flv h video youtube video using ffmpeg. The original video test.
The new stream is unreadable by any player including ffplay and gives an error with ffprobe : test. With that option ffmpeg perform a simple "mux" of each h sample in a NAL unit. Learn more. Asked 6 years, 6 months ago. Active 6 years, 6 months ago. Viewed 30k times. I also tried simpler youtube command line: ffmpeg -i test. If I transcode the video ffmpeg -i test. You should always include the complete ffmpeg console output s and not just sections.
I edited my question to add the complete console output. Can you add it as an answer or should I do it? Thank you!! Active Oldest Votes. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.
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