ffmpeg h264: VLC could not decode the format "aivx" I am using the following command to make h264 archives of video with ffmpeg:

ffmpeg -i myfile.mov -c:a copy -c:v libx264 -preset slower -crf 20 myfilearchive.mov


To get 10-bit h264 support for capture with decklink, I switched my ffmpeg from a version I downloaded from ffmpeg.org to a version I built using the media autobuild suite.  Now, however, when I run the same command to make an archive video, the output can't be played in VLC.

This is the error I get in VLC:


  Codec not supported: VLC could not decode the format "aivx" (No
  description for this codec)


This is the output (from MediaInfo) for an archive video made with the ffmpeg I downloaded from ffmpeg.org:

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High 4:2:2@L5.2
Format settings, CABAC                   : Yes
Format settings, ReFrames                : 8 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 5 min 4 s
Bit rate                                 : 26.3 Mb/s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 29.970 (30000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:2
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.106
Stream size                              : 953 MiB (92%)
Writing library                          : x264 core 148 r2721 72d53ab
Encoding settings                        : cabac=1 / ref=8 / deblock=1:0:0 / analyse=0x3:0x133 / me=umh / subme=9 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=12 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=60 / rc=crf / mbtree=1 / crf=20.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Language                                 : English


This is the output (from MediaInfo) for an archive video made with the ffmpeg I built locally:

Video
ID                                       : 1
Format                                   : aivx
Codec ID                                 : aivx
Duration                                 : 4 min 30 s
Bit rate                                 : 27.2 Mb/s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 29.970 (30000/1001) FPS
Bits/(Pixel*Frame)                       : 0.110
Stream size                              : 878 MiB (92%)
Language                                 : English


Can I get playback in VLC by changing the command used to encode the videos?  (I want to use h264, but it doesn't have to be 10-bit for the archive.)  Or should I just use one ffmpeg for capture (with 10-bit support), and another ffmpeg for archival output (in other words, use the ffmpeg.org binary ffmpeg to do my archives)?
aivx is simply a specific tag for 4K H.264 streams. Surprising that VLC doesn't probe the stream.

Try with

ffmpeg -i myfile.mov -c:a copy -c:v libx264 -preset slower -crf 20 -vtag avc1 myfilearchive.mov


In some cases, ffmpeg may fail to set the tag without warning. Add -strict -2 if that's the case.