Download format change from mp4 to mkv after install libav-tools

[sunshineo]

Please follow the guide below

• You will be asked some questions and requested to provide some information, please read them carefully and answer honestly
• Put an x into all the boxes [ ] relevant to your issue (like this: [x])
• Use the Preview tab to see what your issue will actually look like

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Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2018.05.18. If it's not, read this FAQ entry and update. Issues with outdated version will be rejected.

• I've verified and I assure that I'm running youtube-dl 2018.05.18

Before submitting an issue make sure you have:

• At least skimmed through the README, most notably the FAQ and BUGS sections
• Searched the bugtracker for similar issues including closed ones
• Checked that provided video/audio/playlist URLs (if any) are alive and playable in a browser

What is the purpose of your issue?

• Bug report (encountered problems with youtube-dl)

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Before

root@2ef7c3ee568a:/home# youtube-dl --version
2018.05.18
root@2ef7c3ee568a:/home# youtube-dl -v --id https://www.youtube.com/watch?v=r43LhSUUGTQ
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-v', '--id', 'https://www.youtube.com/watch?v=r43LhSUUGTQ']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2018.05.18
[debug] Python version 3.6.5 (CPython) - Linux-4.9.87-linuxkit-aufs-x86_64-with-debian-8.10
[debug] exe versions: none
[debug] Proxy map: {}
[youtube] r43LhSUUGTQ: Downloading webpage
[youtube] r43LhSUUGTQ: Downloading video info webpage
[youtube] r43LhSUUGTQ: Extracting video information
[debug] Default format spec: best/bestvideo+bestaudio
[debug] Invoking downloader on 'https://r12---sn-nx57ynl7.googlevideo.com/videoplayback?initcwndbps=1381250&mt=1526942148&mn=sn-nx57ynl7%2Csn-n4v7knll&mm=31%2C26&itag=22&ms=au%2Conr&lmt=1508384570199637&mv=m&ipbits=0&source=youtube&ratebypass=yes&key=yt6&sparams=dur%2Cei%2Cid%2Cinitcwndbps%2Cip%2Cipbits%2Citag%2Clmt%2Cmime%2Cmm%2Cmn%2Cms%2Cmv%2Cpl%2Cratebypass%2Crequiressl%2Csource%2Cexpire&fvip=5&signature=8C2FDFF975E65996A1B63464DCA21F4D8934FDD4.DCD7FB454F418EA20F21CBE986C39221100A2407&pl=21&mime=video%2Fmp4&requiressl=yes&ip=216.243.42.133&ei=MkoDW_imJ9Kt-gPCk6qABQ&id=o-APexre-EAHYe6jJR03OSq_BAMaoB39Zrt7E73H9xyd8u&expire=1526963858&c=WEB&dur=145.101'
[download] Destination: r43LhSUUGTQ.mp4
[download] 100% of 17.53MiB in 00:02
root@2ef7c3ee568a:/home# ls
r43LhSUUGTQ.mp4
root@2ef7c3ee568a:/home#

After apt-get install -y libav-tools

root@2ef7c3ee568a:/home# youtube-dl --version
2018.05.18
root@2ef7c3ee568a:/home# youtube-dl -v --id https://www.youtube.com/watch?v=r43LhSUUGTQ
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-v', '--id', 'https://www.youtube.com/watch?v=r43LhSUUGTQ']
[debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2018.05.18
[debug] Python version 3.6.5 (CPython) - Linux-4.9.87-linuxkit-aufs-x86_64-with-debian-8.10
[debug] exe versions: avconv 11.12-6, avprobe 11.12-6
[debug] Proxy map: {}
[youtube] r43LhSUUGTQ: Downloading webpage
[youtube] r43LhSUUGTQ: Downloading video info webpage
[youtube] r43LhSUUGTQ: Extracting video information
[debug] Default format spec: bestvideo+bestaudio/best
WARNING: Requested formats are incompatible for merge and will be merged into mkv.
[debug] Invoking downloader on 'https://r12---sn-nx57ynl7.googlevideo.com/videoplayback?pcm2=no&mv=m&mt=1526942272&ms=au%2Conr&ei=iEoDW9TUEtDz-gOS66vICg&expire=1526963944&requiressl=yes&mn=sn-nx57ynl7%2Csn-n4v7knll&mm=31%2C26&ipbits=0&itag=137&clen=31552346&id=o-AM2A5GmsvdY3JhkbmUZszB0AbU8eXAQHoH2aUetBsJ2G&key=yt6&ip=216.243.42.133&lmt=1508384370701912&keepalive=yes&dur=145.044&aitags=133%2C134%2C135%2C136%2C137%2C160%2C242%2C243%2C244%2C247%2C248%2C278&mime=video%2Fmp4&sparams=aitags%2Cclen%2Cdur%2Cei%2Cgir%2Cid%2Cinitcwndbps%2Cip%2Cipbits%2Citag%2Ckeepalive%2Clmt%2Cmime%2Cmm%2Cmn%2Cms%2Cmv%2Cpcm2%2Cpl%2Crequiressl%2Csource%2Cexpire&fvip=5&signature=36C8C457F8BAD0F205CBE3E70015A70AB8140BEF.2D89480820DD67E3225C52901078CA3B20682ADA&c=WEB&initcwndbps=1386250&gir=yes&pl=21&source=youtube&ratebypass=yes'
[download] Destination: r43LhSUUGTQ.f137.mp4
[download] 100% of 30.09MiB in 00:04
[debug] Invoking downloader on 'https://r12---sn-nx57ynl7.googlevideo.com/videoplayback?pcm2=no&mv=m&mt=1526942272&ms=au%2Conr&ei=iEoDW9TUEtDz-gOS66vICg&expire=1526963944&requiressl=yes&mn=sn-nx57ynl7%2Csn-n4v7knll&mm=31%2C26&ipbits=0&itag=251&clen=2604611&id=o-AM2A5GmsvdY3JhkbmUZszB0AbU8eXAQHoH2aUetBsJ2G&key=yt6&ip=216.243.42.133&lmt=1493087276904561&keepalive=yes&dur=145.061&mime=audio%2Fwebm&sparams=clen%2Cdur%2Cei%2Cgir%2Cid%2Cinitcwndbps%2Cip%2Cipbits%2Citag%2Ckeepalive%2Clmt%2Cmime%2Cmm%2Cmn%2Cms%2Cmv%2Cpcm2%2Cpl%2Crequiressl%2Csource%2Cexpire&fvip=5&signature=67575D39B646D79F733BBE7E47C284560D5322FF.B3014B05D124D13D59B74AD1C157346A9655AF61&c=WEB&initcwndbps=1386250&gir=yes&pl=21&source=youtube&ratebypass=yes'
[download] Destination: r43LhSUUGTQ.f251.webm
[download] 100% of 2.48MiB in 00:01
[ffmpeg] Merging formats into "r43LhSUUGTQ.mkv"
[debug] ffmpeg command line: avconv -y -i file:r43LhSUUGTQ.f137.mp4 -i file:r43LhSUUGTQ.f251.webm -c copy -map 0:v:0 -map 1:a:0 file:r43LhSUUGTQ.temp.mkv
Deleting original file r43LhSUUGTQ.f137.mp4 (pass -k to keep)
Deleting original file r43LhSUUGTQ.f251.webm (pass -k to keep)
root@2ef7c3ee568a:/home# ls
r43LhSUUGTQ.mkv
root@2ef7c3ee568a:/home#

[dstftw]

This is expected behavior.

[sunshineo]

@dstftw What should I do? I want mp4? I tried to use --merge-output-format mp4 but it is super slow for me and sometimes simply stuck when the original format is already mp4

I installed the tool so I can try to convert to mp4 only when needed

[Hrxn]

Format selection with -f

[sunshineo]

I confirm that -f works very well. Thank you to @Hrxn and @dstftw