FFV1 codec_tag metadata missing in recently captured files (ffprobe QC fails)

[BleakleyMcD]

Our QC step is flagging the FFV1 codec tag fields on freshly captured files.

The video stream is FFV1, but the codec_tag metadata is unset.

ffprobe output from QC:

Some specified ffprobe fields or values are missing or don't match:
Metadata field codec_tag_string has a value of: [0][0][0][0]
The expected value is: FFV1
Metadata field codec_tag has a value of: 0x0000
The expected value is: 0x31564646
Encoder Settings No Encoder Settings found, No Signal Flow data embedded

JPC_AV_03796_capture_options.log

computer_name: Mac-68
computer_model_name: Mac mini
computer_model_id: Mac16,10
computer_processor_name: 
computer_processor_speed: 
computer_processor_count: 
computer_memory: 16 GB
computer_serial: RL4K4FXKGK
computer_cores: 10
user_name: digitizer_a
operating_system_VERSION: Darwin Kernel Version 24.3.0: Thu Jan  2 20:22:58 PST 2025; root:xnu-11215.81.4~3/RELEASE_ARM64_T8132
vrecord version: 2026-03-02
datetime_start: 2026-06-01T13:36:43
capture_device_node: /dev/disk3
capture_device_protocol: Apple Fabric
capture_device_name: APPLE SSD AP0256Z
capture_device_block_size: 4096 Bytes
capture_device_location: Internal
capture_device_partition_type: 41504653-0000-11AA-AA11-00306543ECAC
capture_device_partition_name: APFS
capture_device_volume_uuid: DC2C1AD8-D4FF-4D36-9376-524CB49BE049
capture_device_volume_available: 
capture_device_volume_total: 
FILE_PATH: /Users/digitizer_a/Desktop/Ingestion/JPC_AV_03796/JPC_AV_03796.mkv
video_card_name: UltraStudio 4K Mini
VIDEO_INPUT_CHOICE: Composite
AUDIO_INPUT_CHOICE: Analog
VIDEO_BIT_DEPTH_CHOICE: 10 bit
AUDIO_MAPPING_CHOICE: 2 Stereo Tracks (Channels 1 & 2 -> 1st Track Stereo, Channels 3 & 4 -> 2nd Track Stereo)
STANDARD_CHOICE: NTSC
ASPECT_RATIO_CHOICE: 4/3
NTSC_43_SAR_CHOICE: 10/11
NTSC_169_SAR_CHOICE: 40/33
PAL_43_SAR_CHOICE: 12/11
PAL_169_SAR_CHOICE: 16/11
WAVEFORM_SCALE_CHOICE: digital
SIGNAL_VIEW_CHOICE: Broadcast Range
SIGNAL_INT_CHOICE: auto
MONITOR_AUDIO_CHOICE: Yes
PLAYBACKVIEW_CHOICE: Audio + Video
CONTAINER_CHOICE: Matroska
VIDEO_CODEC_CHOICE: FFV1 version 3
AUDIO_CODEC_CHOICE: 24-bit FLAC
QCTOOLSXML_CHOICE: No
EMBED_LOGS_CHOICE: No


TECHNICIAN: Colley, Tom
Record command: /opt/homebrew/bin/ffmpeg-ma -nostdin -nostats -timecode_format all -guess_layout_max 0 -loglevel warning -f decklink -signal_loss_action none -audio_input analog -video_input composite -format_code ntsc -channels 8 -audio_depth 32 -raw_format yuv422p10 -i UltraStudio 4K Mini -c:v ffv1 -level 3 -g 1 -slicecrc 1 -c:a flac -sample_fmt s32 -bits_per_raw_sample:a 24 -map_metadata 0:s:v:0 -metadata:s:v:0 encoder=FFV1 version 3 -metadata creation_time=now -filter_complex [0:v:0]setparams=range=limited:color_primaries=smpte170m:color_trc=bt709:colorspace=smpte170m:field_mode=auto,setsar=10/11,readeia608=lp=1:spw=0.27,metadata=mode=print:key=lavfi.readeia608.0.cc:file=/tmp/vrecord.34bJki.eia608.txt[vout];[0:a:0]asplit[orig],pan=stereo| c0=c0 | c1=c1[stereo1];[0:a:0]pan=stereo| c0=c2 | c1=c3[stereo2] -map [vout] -map [orig] -map [stereo1] -map [stereo2] -f tee [f=matroska:select=v,a\\:1,a\\:2]/Users/digitizer_a/Desktop/Ingestion/JPC_AV_03796/JPC_AV_03796.mkv|[f=nut:onfail=abort:select=v,a\\:1,a\\:2,a\\:0]pipe:1 -an -f framemd5 /Users/digitizer_a/Desktop/Ingestion/JPC_AV_03796/JPC_AV_03796.framemd5
Playback command: /opt/homebrew/bin/ffplay-ma -v info -hide_banner -stats -autoexit -window_title mode:record - video:'composite' audio:'analog' - to end recording press q, esc, or close video window -f lavfi amovie='pipe\:0':streams=dv+da[vid][aud],    [aud]asplit=2[original_audio][audio_to_map];[audio_to_map]pan=4c|c0=c0|c1=c1|c2=c2|c3=c3[out1];    [original_audio]showvolume=t=0:dm=5400:rate=30000/1001,drawtext=fontfile=/System/Library/Fonts/Supplemental/Andale Mono.ttf:text='L(1)':fontcolor=white:fontsize=18:x=0:y=0,drawtext=fontfile=/System/Library/Fonts/Supplemental/Andale Mono.ttf:text='R(1)':fontcolor=white:fontsize=18:x=0:y=20,drawtext=fontfile=/System/Library/Fonts/Supplemental/Andale Mono.ttf:text='L(2)':fontcolor=white:fontsize=18:x=0:y=40,drawtext=fontfile=/System/Library/Fonts/Supplemental/Andale Mono.ttf:text='R(2)':fontcolor=white:fontsize=18:x=0:y=60[aud2];    [vid]split=5[a][b][c][d][e];    [a]copy[a1];    [b]field=top,    format=yuv422p,    waveform=scale=digital:intensity=0.1:mode=column:mirror=1:c=1:f=lowpass:e=instant:graticule=green:flags=numbers+dots[b1];    [c]field=bottom,    format=yuv422p,    waveform=scale=digital:intensity=0.1:mode=column:mirror=1:c=1:f=lowpass:e=instant:graticule=green:flags=numbers+dots[c1];    [d]    format=yuv422p,    vectorscope=i=0.04:mode=color2:c=1:envelope=instant:graticule=green:flags=name,    scale=512:512,    drawbox=w=9:h=9:t=1:x=128-3:y=512-452-5:c=sienna@0.8,    drawbox=w=9:h=9:t=1:x=160-3:y=512-404-5:c=sienna@0.8,    drawbox=w=9:h=9:t=1:x=192-3:y=512-354-5:c=sienna@0.8,    drawbox=w=9:h=9:t=1:x=224-3:y=512-304-5:c=sienna@0.8,    drawgrid=w=32:h=32:t=1:c=white@0.1,    drawgrid=w=256:h=256:t=1:c=white@0.2[d1];    [e]scale=512:ih,signalstats=out=brng[e1];    [a1][b1][c1][e1][d1]xstack=inputs=5:layout=0_0|0_h0|0_h0+h1|w0_0|w0_h0[vidstack];    [vidstack][aud2]overlay=10:10:format=yuv444[out0]
Record exit code: 224
Playback exit code: 0
datetime_end: 2026-06-01T13:42:03
PTS_DISCONTINUITY: none
mediaconch_outcome: passed

[dericed]

Oh hey, this is because of a change that happened in how FFmpeg marks that a Matroska file uses FFV1. Back in the old days FFV1 wasn't registered in the Matroska Codec Registry so in the case of no registration the b-plan was to use the V_MS/VFW/FOURCC codec identifier and then use the AVI style, BITMAPINFOHEADER, in the Codec Private Data to initialize everything. Later V_FFV1 was added to the Matroska Codec Registry. Then FFmpeg stayed with the V_MS/VFW/FOURCC mapping when writing but would be able to read V_FFV1, after enough time for everything to update their Matroska demuxer, FFmpeg switched from writing V_MS/VFW/FOURCC for FFV1 to writing V_FFV1.

Here's the old structure (via mkvnote -a oldway.mkv:

|+ Tracks
| + Track
|  + Track number: 1 (track ID for mkvmerge & mkvextract: 0)
|  + Track UID: 1
|  + "Lacing" flag: 0
|  + Language: und
|  + Track type: video
|  + Default duration: 00:00:00.033366666 (29.970 frames/fields per second for a video track)
|  + Codec ID: V_MS/VFW/FOURCC
|  + Video track
|   + Pixel width: 720
|   + Pixel height: 486
|   + Display width: 648
|   + Display height: 486
|  + Codec's private data: size 240 (FourCC: 0x46465631 "FFV1")

and the new way

| + Track
|  + Track number: 1 (track ID for mkvmerge & mkvextract: 0)
|  + Track UID: 2752370543699111236
|  + "Lacing" flag: 0
|  + Language: und
|  + "Default track" flag: 0
|  + Codec ID: V_FFV1
|  + Track type: video
|  + Default duration: 00:00:00.033366666 (29.970 frames/fields per second for a video track)
|  + Video track
|   + Pixel width: 720
|   + Pixel height: 486
|   + Interlaced: 1
|   + Field order: 14 (bff (interleaved; bottom field displayed first; fields are interleaved in storage with the top line of the top field stored first))
|   + Display width: 400
|   + Display height: 297
|   + Display unit: 3 (aspect ratio)
|   + Video color information
|    + Color transfer: 1
|    + Color matrix coefficients: 6
|    + Color primaries: 6
|    + Color range: 1
|  + Maximum block additional ID: 101
|  + Block addition mapping
|   + Block addition ID type: 121 (SMPTE ST 12-1 timecodes)
|   + Block addition ID value: 101
|  + EBML void: size 68
|  + Codec's private data: size 200

A validator for FFV1 in MKV should permit both V_FFV1 as a codec id and V_MS/VFW/FOURCC as the codec id with the fourcc "FFV1" in private data.

[BleakleyMcD]

@eddycolloton @DSohl