Ubuntu – Is it possible to only download a single frame from a youtube video

ffmpegopencvyoutube-dl

Let me explain what I had set up. I've been using pytube (Python module) to download videos from YouTube. I would then extract a few random frames from the video and save them as jpegs. I don't need the audio, nor the video.

Now, I've been downloading tens of thousands of videos and then deleting them just to grab a couple of random frames per video. This seemed wasteful and cost a fair bit too. Is there a way to just download the frames themselves without having to download the video?

I would guess something like youtube-dl combined with ffmpeg would do the trick, but I can't find an example online to do that. There is a solution to download a random sample of video which would reduce network bandwidth consumption a good deal, but I want something more efficient and less time consuming. Any help would be appreciated.

WARNING: Could not send HEAD request to https://www.youtube.com/watch\?v\=oHg5SJYRHA0: HTTP Error 404: Not Found ERROR: Unable to download webpage: HTTP Error 404: Not Found (caused by HTTPError()); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see https://yt-dl.org/update on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output. ffmpeg version 3.4.6-0ubuntu0.18.04.1 Copyright (c) 2000-2019 the FFmpeg developers built with gcc 7 (Ubuntu 7.3.0-16ubuntu3) configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared WARNING: library configuration mismatch avcodec configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared --enable-version3 --disable-doc --disable-programs --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libtesseract --enable-libvo_amrwbenc libavutil 55. 78.100 / 55. 78.100 libavcodec 57.107.100 / 57.107.100 libavformat 57. 83.100 / 57. 83.100 libavdevice 57. 10.100 / 57. 10.100 libavfilter 6.107.100 / 6.107.100 libavresample 3. 7. 0 / 3. 7. 0 libswscale 4. 8.100 / 4. 8.100 libswresample 2. 9.100 / 2. 9.100 libpostproc 54. 7.100 / 54. 7.100 -vframes: No such file or directory

Best Answer

Using a combination of this answer and this answer the following should be able to do what you want:

ffmpeg -ss "$screenshot_time" -i $(youtube-dl -f 22 --get-url "$youtube_url") -vframes 1 -q:v 2 "$output_file"

ffmpeg's -ss option is used here as an input option which is the fastest method available. It can be used as an output option, which will take a lot more time, but avoids the accidental artifact creation that the input version occasionally generates.

-ss position (input/output)

When used as an input option (before -i), seeks in this input file to position. Note the in most formats it is not possible to seek exactly, so ffmpeg will seek to the closest seek point before position. When transcoding and -accurate_seek is enabled (the default), this extra segment between the seek point and position will be decoded and discarded. When doing stream copy or when -noaccurate_seek is used, it will be preserved.

When used as an output option (before an output filename), decodes but discards input until the timestamps reach position.

position may be either in seconds or in hh:mm:ss[.xxx] form.

The -i option means to use the following as input to ffmpeg, here we use Bash's command substitution to use the output of youtube-dl.
-vframes 1 sets the number of output frames to 1.
-q:v 2 controls output quality. The full range is a linear scale of 1-31 where a lower value results in a higher quality. 2-5 is the range recommended in the source answer used for the ffmpeg part of this answer.
"$screenshot_time" should be replaced with the timestamp of the clip you wish to capture in the from shown above.
"$output_file" should be replaced with the path to your output file, screenshot.jpeg or similar perhaps.

In terms of the youtube-dl command, -f 22 downloads as the best possible quality mp4 format, and the "$youtube_url" should be replaced with the URL of the video.

Related Solutions

Ubuntu – How to get good quality when converting digital video

It is well worth running a deinterlacing video filter during your video encode and this may very well lessen some of the odd screen effects that you are seeing in your output video. A second thought, unrelated to motion artefact but well worth adding in, is the use of a de-noising filter.

1. Deinterlacing:

For FFmpeg the best and fastest choice is yadif which in the usual quirky geek fashion simply stands for 'Yet Another DeInterlacing Filter'!

yadif can be used with no options or you can specify an option for each of 3 fields:

mode: The basic interlacing mode to adopt
parity: The picture field parity assumed for the input interlaced video
deint: Specify which frames to deinterlace

The safe defaults can be specified on the FFmpeg command line as:

-vf yadif=0:-1:0

If you wish to alter these all of the deeper detail is contained here:

FFmpeg Filter Documentation: yadif
https://ffmpeg.org/ffmpeg-filters.html#yadif-1

A further deinterlacing filter called mcdeint (motion-compensation deinterlacing) can also be applied but you may find this painfully slow. A typical command line for use of this filter would be:

-vf yadif=1:-1:0,mcdeint=2:1:10

And again the fine detail of the mcdeint options can be seen in the FFmpeg documentation:

FFmpeg Filter Documentation: mcdeint
https://ffmpeg.org/ffmpeg-filters.html#mcdeint

2. Denoising:

A final though that may well be worth some experimentation is the use of a denoising filter, although this should not effect motion artefact it is still a well worth addition. Under FFmpeg there are a few choices but one well worth looking at is nlmeans (denoise frames using Non-Local Means algorithm). You will need the very latest FFmpeg for this one.

To use this in the easiest command line try the following:

-vf yadif=0:-1:0,nlmeans

There is a hit with nlmeans in terms of encoding time, not as severe a penalty as is seen with mcdeint but still a consideration...

If you have an older copy of FFmpeg with no access to this newest filter there is an older denoise filter that can safely be used with trust in the sane defaults:

-vf yadif=0:-1:0,hqdn3d

I note on my own system that hqdn3d is very, very much faster than the newer nlmeans. Better? Well I suspect that is a debate for another forum :)

And hopefully a combination of any of these thoughts will solve your problem...

References:

Ubuntu – Download everything from a YouTube video using youtube-dl

The relevant options you need:

# Filesystem
--write-annotations
--write-description
--write-info-json

# Thumbnail images
--write-all-thumbnails

# Video format
--format bestvideo+bestaudio/best
--merge-output-format mkv

# Subtitle
--all-subs
--write-auto-sub
--write-sub

# Post-processing
--add-metadata
--embed-subs

Copy that to your config file (either /etc/youtube-dl.conf or ~/.config/youtube-dl/config).

Using that configuration, I downloaded this video and youtube-dl wrote the following files:

$ ls
The Problem with Time & Timezones - Computerphile.annotations.xml
The Problem with Time & Timezones - Computerphile.description
The Problem with Time & Timezones - Computerphile.info.json
The Problem with Time & Timezones - Computerphile.jpg
The Problem with Time & Timezones - Computerphile.mkv

I can't post mediainfo's output here because it exceeds the characters limit, but you can see it in github.

I also want to download the video/audio in the highest quality possible, with no quality loss.

youtube-dl downloads videos at the highest quality possible by default, but you can force this behavior using --format bestvideo+bestaudio/best.

Even though it's not YouTube, I did also want to download some of my udemy courses I've bought so I can watch them while I'm on a long road trip.

Please read the article Can I Download a Course to my Computer?:

By default, complete courses are not downloadable from a computer. We do this out of concerns for piracy.

Please note that you can always save courses for offline viewing on the Udemy mobile app. For information on how to download video lectures to your iOS mobile device, please click here. For steps on how to download videos for offline viewing on an Android device, click here.

I have ffmpeg installed, and I heard that you need this for lossless downloads from YouTube, but I'm not sure how to link it with youtube-dl.

youtube-dl uses avconv by default, but --prefer-ffmpeg let you use ffmpeg instead. Anyway, this option is not needed for "lossless downloads". In the example I provided, youtube-dl only used ffmpeg to merge all the downloaded formats into a single mkv file.

Best Answer

Related Solutions

Ubuntu – How to get good quality when converting digital video

Ubuntu – Download everything from a YouTube video using youtube-dl

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