[FFmpeg-user] Cleaning up codeline to grab and record HDV video using Firewire/libiec61883

[Terje J. Hanssen]

Thanks for the feedback and  comments.

Den 30.06.2025 01:00, skrev BloodMan:
> Hi,
>
>
> W dniu 2025-06-29 o 23:29, Terje J. Hanssen pisze:
>> a) Why so when the standard .M2T is 25 Mbps?
>
> Because of:
> > Stream mapping:
> >    Stream #0:2 -> #0:0 (mpeg2video (native) -> mpeg1video (native))
>                               ^                      ^
> Caused by:
> > ffmpeg -hide_banner -f iec61883 -i auto -dvbuffer 100000 out.mpg
>                                                                ^^^
> (yeah, do not use .mpg without codec tweaking, IMHO do not use at all ;)


Seemingly the most important missing part of the documentation's example 
code line

ffmpeg -f iec61883 -i auto -dvbuffer 100000 out.mpg

is "-c copy"

HDV 1080i50 stream is MPEG-2/ MP at H-14 video and MP2 audio
The container can be .mpg or .m2t

I have tried additional combination as follows:

.mpg w/o  "-c copy" ==> mpeg1video, mp2 audio
.mpg with "-c copy" ==> mpeg2video, mp2 audio

.mp4 w/o  "-c copy" ==> h264 video, aac audio
.mp4 with "-c copy" ==> mpeg2video, mp2 audio

-----------

In addition I created a "BDAV" format using hdv video copy and mp2 audio 
to pcm_bluray transcoding.

ffmpeg -hide_banner -f iec61883 -i auto -c:v copy -c:a pcm_bluray 
-mpegts_m2ts_mode 1 -t 30 Out_hdv.m2ts

[mpeg2video @ 0x556b164f54c0] Invalid frame dimensions 0x0.
     Last message repeated 4 times
[iec61883 @ 0x556b164d6a40] Could not find codec parameters for stream 0 
(Unknown: none): unknown codec
Consider increasing the value for the 'analyzeduration' (0) and 
'probesize' (5000000) options
[iec61883 @ 0x556b164d6a40] Could not find codec parameters for stream 3 
(Unknown: none ([160][0][0][0] / 0x00A0)): unknown codec
Consider increasing the value for the 'analyzeduration' (0) and 
'probesize' (5000000) options
[iec61883 @ 0x556b164d6a40] Could not find codec parameters for stream 4 
(Unknown: none ([161][0][0][0] / 0x00A1)): unknown codec
Consider increasing the value for the 'analyzeduration' (0) and 
'probesize' (5000000) options

Input #0, iec61883, from 'auto':
   Duration: N/A, start: 1796.421533, bitrate: 25384 kb/s
   Program 100
   Stream #0:2: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), 
yuv420p(tv, bt709, top first), 1440x1080 [SAR 4:3 DAR 16:9], 25000 kb/s, 
25 fps, 25 tbr, 90k tbn
       Side data:
         cpb: bitrate max/min/avg: 25000000/0/0 buffer size: 7340032 
vbv_delay: N/A
   Stream #0:1: Audio: mp2 (mp3float) ([3][0][0][0] / 0x0003), 48000 Hz, 
stereo, fltp, 384 kb/s
   Stream #0:3: Unknown: none ([160][0][0][0] / 0x00A0)
   Stream #0:4: Unknown: none ([161][0][0][0] / 0x00A1)
   No Program
   Stream #0:0: Unknown: none
Stream mapping:
   Stream #0:2 -> #0:0 (copy)
   Stream #0:1 -> #0:1 (mp2 (native) -> pcm_bluray (native))
Press [q] to stop, [?] for help

Output #0, mpegts, to 'Out_hdv.m2ts':
   Metadata:
     encoder         : Lavf61.7.100
   Stream #0:0: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), 
yuv420p(tv, bt709, top first), 1440x1080 [SAR 4:3 DAR 16:9], q=2-31, 
25000 kb/s, 25 fps, 25 tbr, 90k tbn
       Side data:
         cpb: bitrate max/min/avg: 25000000/0/0 buffer size: 7340032 
vbv_delay: N/A
   Stream #0:1: Audio: pcm_bluray, 48000 Hz, stereo, s16, 128 kb/s
       Metadata:
         encoder         : Lavc61.19.101 pcm_bluray
[out#0/mpegts @ 0x556b16516b40] video:90364KiB audio:5648KiB 
subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: 
5.467366%
frame=  740 fps= 26 q=-1.0 Lsize=  101262KiB time=00:00:30.00 
bitrate=27651.3kbits/s speed=1.06x


>
>
>
>> b) There are also warnings regarding streams 0, 3, 4 ?
>
> Program/technical/cam-internal data
> (maybe text, geo, title, etc data, ignore in general)
>
>
>
>> a) Adding "-c copy" solves the output bitrate = input bitrate = 25 Mbps
>
> Yup, copy or mp4 codec it's probably best way...
>
>
>> c) Trying to increase the value for the 'analyzeduration' (0) and 
>> 'probesize' are not successful?
>
> no success because the streams do not contain recognizable data
>
>
>