Codec Private Data Does Not Match (Merging Files with MKVToolnix)

[koberulz]

The track number 0 from the file '2.mp4' can probably not be appended correctly to the track number 0 from the file '1.mp4': The codec's private data does not match (lengths: 44 and 44). Please make sure that the resulting file plays correctly the whole time. The author of this program will probably not give support for playback issues with the resulting file.

I'm getting the same error regarding appending file 2 to file 3, and then the rest of them are fine.

MediaInfo seems the same:

General
Complete name                            : 1.mp4
Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42 (mp42/mp41/isom/avc1)
File size                                : 47.2 MiB
Duration                                 : 2 min 32 s
Overall bit rate mode                    : Variable
Overall bit rate                         : 2 592 kb/s
Encoded date                             : UTC 2013-04-23 02:26:50
Tagged date                              : UTC 2013-04-23 02:26:50

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L3.1
Format settings, CABAC                   : Yes
Format settings, ReFrames                : 4 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 2 min 32 s
Bit rate                                 : 2 426 kb/s
Width                                    : 1 280 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 29.970 (29970/1000) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.088
Stream size                              : 44.2 MiB (94%)
Writing library                          : x264 core 129 r2245 bc13772
Encoding settings                        : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=12 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=90 / keyint_min=30 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=2pass / mbtree=1 / bitrate=2426 / ratetol=1.0 / qcomp=0.60 / qpmin=5 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=3750 / vbv_bufsize=12500 / nal_hrd=none / ip_ratio=1.40 / aq=1:1.00
Encoded date                             : UTC 2013-04-23 02:26:50
Tagged date                              : UTC 2013-04-23 02:26:50

Audio
ID                                       : 2
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 40
Duration                                 : 2 min 32 s
Source duration                          : 2 min 32 s
Bit rate mode                            : Variable
Bit rate                                 : 158 kb/s
Channel(s)                               : 2 channels
Channel positions                        : Front: L R

General
Complete name                            : 2.mp4
Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42 (mp42/mp41/isom/avc1)
File size                                : 204 MiB
Duration                                 : 10 min 58 s
Overall bit rate mode                    : Variable
Overall bit rate                         : 2 599 kb/s
Encoded date                             : UTC 2013-04-23 13:14:45
Tagged date                              : UTC 2013-04-23 13:14:45

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L3.1
Format settings, CABAC                   : Yes
Format settings, ReFrames                : 4 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 10 min 58 s
Bit rate                                 : 2 437 kb/s
Width                                    : 1 280 pixels
Height                                   : 720 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 29.970 (29970/1000) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.088
Stream size                              : 191 MiB (94%)
Writing library                          : x264 core 129 r2245 bc13772
Encoding settings                        : cabac=1 / ref=3 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=12 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=90 / keyint_min=30 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=2pass / mbtree=1 / bitrate=2437 / ratetol=1.0 / qcomp=0.60 / qpmin=5 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=3750 / vbv_bufsize=12500 / nal_hrd=none / ip_ratio=1.40 / aq=1:1.00
Encoded date                             : UTC 2013-04-23 13:14:45
Tagged date                              : UTC 2013-04-23 13:14:45

Audio
ID                                       : 2
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 40
Duration                                 : 10 min 58 s
Source duration                          : 10 min 58 s
Bit rate mode                            : Variable
Bit rate                                 : 158 kb/s
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 kHz
Frame rate                               : 43.066 FPS (1024 spf)
Compression mode                         : Lossy
Stream size                              : 12.4 MiB (6%)
Source stream size                       : 12.4 MiB (6%)
Encoded date                             : UTC 2013-04-23 13:14:45
Tagged date                              : UTC 2013-04-23 13:14:45

And even the non-matching numbers are identical. It creates the file but it won't play back properly, as implied.

Is there anything I can do to get file 2 to match the rest? Just trying to combine about ten shorter videos, with chapter markers in between.

[sneaker]

Is there anything I can do to get file 2 to match the rest?

Re-encode to make it match the first. MediaInfo doesn't show detailed info about H.264 headers (PPS/SPS). You'd need a more in-depth H.264 analyzer like e.g. Zond. Maybe x264's header optimization resulted in different headers (--stitchable option didn't exist yet in revision 2245).

Workaround can be to spread SPS/PPS to every keyframe. Try ffmpeg's concat demuxer instead of mkvmerge for appending (there are more options, e.g. run dump_extra filter filter on all source files individually, then append while ignoring mkvmerge warning).

[koberulz]

What's Zond and where do I find it? Googling turns up nothing video-related.

I tried the concat demuxer and had the same playback issues as with the mkvmerge version.

[sneaker]

Then try dump_extra.

[koberulz]

So I have to run that command on all of them, then the concat command? Is there a way to batch them, I have ten files here.

[sneaker]

I would test with two files first. Then if you are successful try batching.

md "work_folder"
for %%a in (*.mp4) do ffmpeg -y -i "%%~a" -map 0 -c copy -bsf:v "h264_mp4toannexb,dump_extra=freq=k" "work_folder\%%~a"
(for %%b in (*.mp4) do @echo file '%%~b') > "work_folder\filelist.txt"
pushd "work_folder"
ffmpeg -y -f concat -safe 0 -i "filelist.txt" -c copy "..\output.mp4"

/edit:
FWIW: I see it's mp4 and not mkv. IIRC mp4 even "officially" allows multiple PPS/SSP and has a way to store them though I don't know which muxer/how. It's probably not needed to make it work but ...

[sneaker]

The following is just some extra info. It's not required to solve the problem but can help find out why there are such problems with certain combinations of input files when appending.

Is there anything I can do to get file 2 to match the rest?

Re-encode to make it match the first. MediaInfo doesn't show detailed info about H.264 headers (PPS/SPS). You'd need a more in-depth H.264 analyzer like e.g. Zond. Maybe x264's header optimization resulted in different headers (--stitchable option didn't exist yet in revision 2245).

What's Zond and where do I find it? Googling turns up nothing video-related.

Zond 265 demo/info can be found here.

But actually ffmpeg also has some features to print SPS/PPS: trace_headers bsf.

ffmpeg -y -i "INPUT" -map 0:v -c copy -frames:v 1 -bsf:v trace_headers -f matroska NUL 2> headers.txt

Then in headers.txt you can find the H.264 header values.
With x264's header optimization "pic_init_qp_minus26" can differ even with the very same command-line. This can cause decoding problems when appending. You can search for it directly:

ffmpeg -y -i "INPUT" -map 0:v -c copy -frames:v 1 -bsf:v trace_headers -f matroska NUL 2>&1 | findstr "pic_init_qp_minus26"

MediaInfo does not display this so it is difficult to find.


When encoding with x264 header optimization can be turned off via --stitchable.

[koberulz]

The dump_extra batch file seems to have fixed the issue. I still get a warning but the file plays back just fine.

[sneaker]

I just realized there is no reason to put this into separate ffmpeg calls. So a short batch would be simply:

(for %%a in (*.mp4) do @echo file '%%a') > "filelist.txt"
ffmpeg -y -f concat -i "filelist.txt" -map 0 -c copy -bsf:v "h264_mp4toannexb,dump_extra=freq=k" "output.mp4"

[koberulz]

Creating the work folder with the individual parts allows me to go back to MKVtoolnixGUI and append them with chapter markers, though. The single output.mp4 file your command creates has no chapters.

[sneaker]

All roads lead to Rome.

[richardpl]

You always can create chapters with ffmpeg ffmetadata demuxer/muxer and some text editing.

[barmah]

sneaker @9, that batch file to merge mp4 files is very useful - thank you!

Is there any chance you could adapt it to merge MKV files? (Just changing mp4 to mkv throughout doesn't work.
(Error parsing bitstream filter sequence 'h264_mkvtoannexb, dump_extra=freq=k': Bitstream filter not found.)

[barmah]

Oops, the modification is easy.

(for %%a in (*.mkv) do @echo file '%%a') > "filelist.txt"
ffmpeg -y -f concat -i "filelist.txt" -map 0 -c copy -bsf:v "h264_mp4toannexb,dump_extra=freq=k" "output.mkv"

The filenames must have no spaces and no special characters.