Merging formats fails - Could not write header for output file #0 (incorrect codec parameters ?)

[przemoc]

youtube-dl -v "https://www.youtube.com/watch?v=OI_YqAdLKFc"

gives following output ending with error:

[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'-v', u'https://www.youtube.com/watch?v=OI_YqAdLKFc']
[debug] Encodings: locale cp1250, fs mbcs, out None, pref cp1250
[debug] youtube-dl version 2015.08.28
[debug] Python version 2.7.8 - Windows-7-6.1.7601-SP1
[debug] exe versions: ffmpeg N-50911-g9efcfbe
[debug] Proxy map: {}
[youtube] OI_YqAdLKFc: Downloading webpage
[youtube] OI_YqAdLKFc: Downloading video info webpage
[youtube] OI_YqAdLKFc: Extracting video information
[youtube] OI_YqAdLKFc: Downloading DASH manifest
[youtube] OI_YqAdLKFc: Downloading DASH manifest
[debug] Invoking downloader on 'https://r2---sn-f5f7ln7l.googlevideo.com/videoplayback?id=388fd8a8074b2857&itag=271&source=youtube&requiressl=yes&ms=au&mv=m&pl=17&mm=31&mn=sn-f5f7ln7l&ratebypass=yes&mime=video/webm&gir=yes&clen=167013643&lmt=1441060274597265&dur=400.566&upn=nET3XzeXQv8&fexp=9407992,9408710,9409069,9409096,9412774,9414936,9415356,9415365,9415485,9416023,9416104,9416126,9416359,9417335,9417707,9417815,9418153,9418356,9418448,9419256,9420021&sver=3&signature=11F9D290A0B9338B1C6507E10B61FC72B0193B55.3F62E7E75D70C259CE9DEA5D4C8F4BD58D20C3E9&key=dg_yt0&mt=1441234081&ip=89.74.38.183&ipbits=0&expire=1441255800&sparams=ip,ipbits,expire,id,itag,source,requiressl,ms,mv,pl,mm,mn,ratebypass,mime,gir,clen,lmt,dur'
[download] Resuming download at byte 18899177
[download] Destination: Linking a MIDI Controller to Track Controls In REAPER-OI_YqAdLKFc.f271.webm

[download]  11.3% of 159.28MiB at 90.91KiB/s ETA 26:31
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[debug] Invoking downloader on 'https://r2---sn-f5f7ln7l.googlevideo.com/videoplayback?id=388fd8a8074b2857&itag=171&source=youtube&requiressl=yes&ms=au&mv=m&pl=17&mm=31&mn=sn-f5f7ln7l&ratebypass=yes&mime=audio/webm&gir=yes&clen=5309970&lmt=1441059508900662&dur=404.531&upn=nET3XzeXQv8&fexp=9407992,9408710,9409069,9409096,9412774,9414936,9415356,9415365,9415485,9416023,9416104,9416126,9416359,9417335,9417707,9417815,9418153,9418356,9418448,9419256,9420021&sver=3&signature=159BD04F7A91CECF8242635D194CF51944240D76.3D539512F168B832C33162CB34434EEF91C3A447&key=dg_yt0&mt=1441234081&ip=89.74.38.183&ipbits=0&expire=1441255800&sparams=ip,ipbits,expire,id,itag,source,requiressl,ms,mv,pl,mm,mn,ratebypass,mime,gir,clen,lmt,dur'
[download] Destination: Linking a MIDI Controller to Track Controls In REAPER-OI_YqAdLKFc.f171.webm

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[ffmpeg] Merging formats into "Linking a MIDI Controller to Track Controls In REAPER-OI_YqAdLKFc.webm"
[debug] ffmpeg command line: ffmpeg -y -i 'Linking a MIDI Controller to Track Controls In REAPER-OI_YqAdLKFc.f271.webm' -i 'Linking a MIDI Controller to Track Controls In REAPER-OI_YqAdLKFc.f171.webm' -c copy -map 0:v:0 -map 1:a:0 'Linking a MIDI Controller to Track Controls In REAPER-OI_YqAdLKFc.temp.webm'
ERROR: Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
Traceback (most recent call last):
  File "youtube_dl\YoutubeDL.pyo", line 1699, in post_process
  File "youtube_dl\postprocessor\ffmpeg.pyo", line 403, in run
  File "youtube_dl\postprocessor\ffmpeg.pyo", line 151, in run_ffmpeg_multiple_files
FFmpegPostProcessorError

Not sure if it is this particular format combination (271+171) or peculiarity of this particular video.

I've downloaded some previous videos of this youtube user in the past and didn't have this problem, but maybe other format combinations were used then.

[jaimeMF]

Using -f 'bestvideo[ext=mp4]+bestaudio[ext=m4a]' could work.

Could you run ffmpeg -y -i 'Linking a MIDI Controller to Track Controls In REAPER-OI_YqAdLKFc.f271.webm' -i 'Linking a MIDI Controller to Track Controls In REAPER-OI_YqAdLKFc.f171.webm' -c copy -map 0:v:0 -map 1:a:0 'Linking a MIDI Controller to Track Controls In REAPER-OI_YqAdLKFc.temp.webm' from the same directory and post the output?

[przemoc]

I have to apologize.

Some time ago I updated ImageMagick via Chocolatey and forgot that it puts its dir at the beginning of PATH env var. This made ImageMagick's old ffmpeg (N-50911-g9efcfbe built on Mar 13 2013 21:26:48 with gcc 4.7.2 (GCC)) being used here. I fixed this and additionally downloaded latest Zeranoe's 64-bit build (N-74798-gd1bdaf3 built with gcc 4.9.3 (GCC)).

Now everything works fine, so I'm closing this.