Questions tagged [webm]

Sponsored by Google, WebM is a new protocol used to convert audio/video files to HTML 5 compliant feeds.

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1answer
59 views

Is there way to increase speed of adding subtitles to a WEBM video?

With MP4 I used this command ffmpeg -i INPUT.mp4 -vf ass=SUBS.ass -c:v libx264 -preset ultrafast -crf 22 -c:a copy OUTPUT.mp4 which has helped to increase the speed. But there are some problems with ...
0
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1answer
165 views

Fixing the length (duration) of a webm file takes too much time by ffmpeg

I have some webm files which lack duration/length. For example when I open one of them (which is about 20 minutes) by vlc media player I see something like this: This is very annoying because I ...
1
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1answer
172 views

ffmpeg fails when executing example command to convert using VP8

I am following the tutorial here, and executing the first example command yeilds an error. The ffmpeg version I have has libvpx and libvorbis enabled. When I run this command: ffmpeg -i aaa.mp4 -c:v ...
0
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0answers
42 views

ffmpeg how to create smallest size of webm VP9 with medium quality

I want to create webm VP9 smallest size of file with medium quality. I use 2 pass command like this. ffmpeg -i test.mkv -c:v libvpx-vp9 -b:v 0 -crf 31 -pass 1 -an -sn -f webm NUL && ^ ffmpeg ...
0
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1answer
112 views

Is it possible to recreate webms with a broken duration?

I've seen a few webms that have very unusual durations, even in the negatives. I've been trying to recreate it with ffmpeg, but I don't know enough of that program to make it work, if it would work at ...
0
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0answers
36 views

Strange video length?

My friend sent me a weird webm video on discord, and it seems to increase in length as I watch it Screenshot of the video's properites I want to recreate it, and think it is because of the video's ...
1
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0answers
57 views

Converting VP9 webm to VP8

I wonder how can I convert VP9 webm to VP8 with FFmpeg or Matroska (matroska would be better) without changing any kind of setting? I just want the output to be exactly same as the input but as VP8 ...
0
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1answer
323 views

How to edit .webm files or convert them to good quality .gif, to edit in GIMP

I have a short scene from some TV show in a .webm format. I wanted to edit it, to create a simple funny animation/meme. I know how to edit .gif in a GIMP frame by frame, so I thought about converting ...
0
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1answer
424 views

Is it possible to make a webm file use a custom duration that is not the actual video's duration? And if so how?

Someone showed me a video where the duration counter would keep changing and another where there was a negative number as the duration, is there anyway to reproduce this? Both were webm files
0
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1answer
164 views

WebM With a Still Image and an Audio

How can I join together a cover and a music into WebM with the best audio quality using ffmpeg? I really can't figure it out.
2
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1answer
307 views

Splitting corrupted webm video file

There's a 50-minute long webm video file which stops playing after about 8th minute. As I don't require the beginning of the video, I decided to split it and get last 30 minutes of it. For that, I ...
1
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1answer
810 views

Lossless VP9 Webm Encoding of PNG Sequence with Alpha in FFmpeg

I'm trying to encode a sequence of 32-bit 8bpc PNG images (RGB with an alpha channel) using the lossless VP9 codec with ffmpeg; specifically: ffmpeg -framerate 60 -i out%04d.png -c:v libvpx-vp9 -...
5
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0answers
2k views

Extracting Opus from WebM losslessly with FFmpeg or MKVToolNix

I have come across a strange problem when remuxing Opus audio stream from WebM to another container like ogg or opus. Running the output files through a spectrum analyzer clearly shows that there is ...
-1
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1answer
2k views

How do I remove all metadata from a WebM file?

I've tried using ffmpeg, but it seems to keep all the metadata I'm actively looking to remove. I'm looking to remove ALL metadata, including length, bitrate, etc. Before you say this isn't possible, ...
0
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1answer
441 views

WEBM video looks correct in browsers, but not in video players

Ive been trying to figure out why a webm video renders incorrectly on my desktop... The correct file can be seen here, however, downloading the file, and trying to play it in VLC/MPC-HC produces a ...
1
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2answers
432 views

Find duplicate WEBM files

I have a large collection of files in webm format. Some of them are duplicates. They have totally different names, but their content is the same. It is annoying to find them by myself and then delete ...
6
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0answers
9k views

FFmpeg - convert WebM/Opus to WAV or FLAC in single step?

I want to create WAV and FLAC audio files from WebM files with Opus audio streams, and I want to do so without further degrading the audio. I am currently using a 2-step process as follows (WAV ...
1
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1answer
1k views

ffmpeg WebM to MP4: awful video quality

I'm trying to convert a WebM video coming from a webcam to an MP4 x264 format. I tried to use this ffmpeg command: ffmpeg -stats -nostdin -y -flags global_header -i "/home/Foto/incoming-video/2017-05-...
2
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0answers
463 views

What is the difference between webm and webm_chunk?

I am asking because I cannot check this myself, when running ffmpeg with "webm_chunk" format I get either "Output file #0 does not contain any stream" or "Could not write header for output file #0" ...
2
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1answer
1k views

FFmpeg fails to convert webm files when h264_nvenc forced

I have been working with below environment. ==>Ubuntu 16.04.3 ==>FFmpeg :3.4.2 -- configuration: --prefix=/usr/local/ffmpeg_new/ --enable-cuda --enable-cuvid --enable-nvenc --enable-nonfree --...
63
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2answers
13k views

What does Matroska have which WebM doesn't, that made the differentiation necessary?

I've read that WebM is essentially a subset of the Matroska format. What does Matroska support that WebM doesn't, which necessitated "christening" a new format rather than just saying "WebM = Matroska ...
6
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1answer
6k views

Is it ok to rename webm (audio-only) files to .opus?

For .webm files obtained with youtube-dl-f bestaudio containing no video stream, is it preferable to run ffmpeg -i input.webm -vn -c:a copy output.opus or can one simply rename the source file, ...
2
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0answers
130 views

How can I inspect the file structure of DASH injected webM files?

So we know after injecting DASH information, WebM files will have the init chunk and index chunk for DASH. How can I inspect the structure of the WebM files to understand the position of these chunks ...
2
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0answers
469 views

Converting video int Webm using ffmpeg, file size

I have found this article from google describing how to convert video into webm https://sites.google.com/a/webmproject.org/wiki/ffmpeg/vp9-encoding-guide I used following command to convert video ...
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1answer
2k views

ffmpeg - Is it possibe to retain real timecodes using -copyts?

It's is a simple task. I want to make a converted clip of a video using -copyts to have it's real timecodes. For example, the converted clip of this command: ffmpeg -hide_banner -ss 57:41.76 -i input....
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2answers
3k views

Extract alpha channel from webm video

I'm trying to extract a mask from a webm video with alpha transparency: ffmpeg -i test.webm -vf "alphaextract" -y output.mp4 But I'm getting an error: [Parsed_alphaextract_2 @ 0x7f924b700d00] ...
0
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0answers
362 views

FFmpeg script to convert all WebM files in a folder to Gif, and then delete the WebM files

I'm using FFmpeg with DirectoryMonitor, a folder watching program. When a webm is added to the folder i want to execute a script to convert all webm files in that folder to gif, and then delete those ...
1
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1answer
607 views

FFMpeg image sequence to video using VP9 encoder

I'm trying to transcode mp4 to webm format in a lossless way. I tried two ways to do that. For that purpose, I extracted mp4 video to image sequences (png). Then, I converted image sequence(without ...
1
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1answer
372 views

How do I transcode/compress mp4 source files on the Linux command line?

I have some rather large mp4s produced by my phone. They aren't very long, so they're probably not very compressed. What's an example of using a command line Linux tool to transcode one of these to ...
4
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1answer
6k views

Correcting for wildly incorrect time of .webm with FFMPEG

I have a file that when I run ffpmeg -i on it will display a time of 351909:41:29.64. I know I didn't record for 40 + years. Any suggestions on what would be the best way to fix this? I ...
0
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1answer
57 views

How can I locate a local html file that has been loaded into the browsers element inspector?

Since there don't seem to be any video players with a seamless loop, I've been opening my webms through Firefox since the webm player is capable of seamless looping. Problem is every time I open a ...
1
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1answer
2k views

How can I convert a series of images to WebM in FFmpeg?

I’ve got a series of JPG images going from 108-AN-001 to 108-AN-045. I need to convert these into a single WebM video file. I've tried this command: ffmpeg -f image2 -i 108-AN-%03d.jpg -vf 12 output....
0
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1answer
2k views

How to mux Vorbis audio and VP8 video into WebM format with ffmpeg?

I have a Vorbis audio and VP8 encoded video, and would like to mux them into WebM format. How do I mux them with FFmpeg, and also set the display aspect ratio to 16:9? I'm using Windows 7 with the ...
0
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1answer
2k views

How to Resize WEBM Videos

I find that a lot of the webm videos (or gifv) on imgur and the like are too small to see (yes, my eyesight is horrible). These types of videos allow for viewing in full screen, but since the source ...
0
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2answers
806 views

Compiling libvorbis with MinGW

I'm attempting to cross compile libvorbis ready to then do the same for libvpx to ultimately compile a windows version of ffmpeg that can handle WebM (along with a few other options that I've yet to ...
-1
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1answer
809 views

FFMPEG conversion from webm to mp4 intermittent on Ubuntu 14.04 [duplicate]

I am trying to convert .webm file that we get from google's screencastify to .mp4 file. I need it to be playable using Windows Media Player. I need it the file to be playing with all the WMP versions ...
3
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3answers
13k views

Conversion from WebM to MP4 in Ubuntu is slow and bad quality

I have used the command ffmpeg -i input.webm -q:v 10 -c:a copy out.mp4 I also tried using avconv instead of ffmpeg. The conversion is successful but the quality is bad. Also it takes a lot of time. ...
25
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3answers
101k views

What's the easiest way to save a GIFV as a simple GIF?

Usually I open the context menu right clicking on the image. Now theres no option for "save image as", just options for the WEBM/MP4 format.
0
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3answers
2k views

combining 1 image + 1 audio using FFmpeg

I want to combine an audio file and one image file into a video. Output will be in .webm format so I will be using libvpx. The video must have one frame with the best/lossless quality. So far I have ...
0
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1answer
2k views

ffmpeg constant rate factor for different webm qualities

So i came across the following question What is the right way to calculate 1080p 720p 360p 240p quality? But that is for H264 MP4 files. For MP4 files i set the -crf constant rate factor as 18 for ...
8
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1answer
708 views

IE will not seek audio/webm file

I'm trying to create a WebM audio file that will play back and seek in all browsers using the HTML5 <audio> tag and MIME type audio/webm. I've found workarounds to get this to work in all ...
0
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0answers
124 views

Video is not playing on any of browsers

When I am trying to open Google Material Design Spec and click on play button nothing happens. Checked on Chrome, Opera, Firefox. When I am trying to open video url directly, first time - it doesn't ...
3
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1answer
11k views

FFmpeg “ass” filter not working

I'm haveing a bit of a problem when trying to use FFmpeg. I've mostly been using it to extract clips from videos and such. However, I've been trying to get some subtitles embedded (hardsubs) into the ...
0
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1answer
898 views

FFmpeg error when doing first pass of WebM encoding: Unrecognized option 'auto-alt-ref'

I'm using OS X Mavericks (10.9.4) and installed ffmpeg from homebrew. When executing this command (assuming input file exists): ffmpeg -i ololo.wmv -vf scale=500:-1 -auto-alt-ref 1 -lag-in-frames 20 ...
2
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1answer
1k views

Why does FFmpeg segment_times create webm files with incorrect duration and start times?

I have a MOV file that I want to split into several smaller files (at certain timestamps in a comma-separated list). I'm simultaneously compressing the video into WEBM files. The command I'm using ...
1
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0answers
162 views

error while merging videos with ffmpeg

I am trying to concat videos with different resolutions using ffmpeg and I am encountering this error shown below while that the video resizes when playing the videos I merge them using ffmpeg with ...
4
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1answer
6k views

How do I split a WebM file without re-encoding?

I have this WebM file that I need to split, but I'd like to do it without re-encoding. Putting it in an MKV container doesn't work, because the point where I need to split it is not a keyframe, so it ...
3
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1answer
4k views

Merge segments from different videos ffmpeg

Could I use ffmpeg to make one video which takes different segments from different videos? 1.webm, 2.webm, 3.webm, 4.webm Those are my 4 video files. I want the 10 seconds from each video. The ...
3
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1answer
3k views

How do you combine multiple ffserver streams into a grid in real time?

I'm trying to set up a CCTV system with ffmpeg/ffserver/zoneminder and want a nice looking 4x4 grid without all the Java applet borders and window dongles on it, just a full screen 4x4 grid. I've ...
19
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1answer
24k views

Converting video to WebM with ffmpeg/avconv

While trying to optimize the size of my home videos I converted some of them to WebM as a test, using Pitivi on Xubuntu. The size difference is significant. The resulting webm-file is only around 10% ...