[FFmpeg-user] XDCAMHD422 Syntax questions - qmin qmax

Christoph Gerstbauer christophgerstbauer at gmail.com
Tue Jun 19 17:15:28 EEST 2018


Hello;

I am using this syntax to generate a XDCAMHD422 file:

ffmpeg -i inputfile.avi -map 0:v -map 0:a  -c:v mpeg2video -r 25 -pix_fmt
yuv422p -s 1920x1080 -aspect 16:9 -minrate 50000k -maxrate 50000k -b:v
50000k -g 12 -flags +ildct+ilme -intra_vlc 1 -dc 10 -non_linear_quant 1 -bf
2 -qmin 1 -qmax 3 -top 1 -dc 10 -bufsize 36408333 -rc_max_vbv_use 1
-rc_min_vbv_use 1 -lmin "1*QP2LAMBDA" -vtag xd5c -c:a pcm_s24le -ar 48000
-vf "setfield=tff" -top 1 D:\targets\ffmpegXDCAM.mxf

I always getting this at the output:
[mpeg2video @ 000002018aae4420] max bitrate possibly too small or try
trellis with large lmax or increase qmax
[mpeg2video @ 000002018aae4420] rc buffer underflow
[mpeg2video @ 000002018aae4420] max bitrate possibly too small or try
trellis with large lmax or increase qmax
[mpeg2video @ 000002018aae4420] rc buffer underflow
[mpeg2video @ 000002018aae4420] max bitrate possibly too small or try
trellis with large lmax or increase qmax
[mpeg2video @ 000002018aae4420] rc buffer underflow
[mpeg2video @ 000002018aae4420] max bitrate possibly too small or try
trellis with large lmax or increase qmax
[mpeg2video @ 000002018aae4420] rc buffer underflow
....

So I reset -qmax to the value 10. (9 -> get warnings again)
After that no warning appears but my main questions here are:

1.) Is my used syntax the right one to generate XDCAMHD422 files?
2.) Is there a specified QMAX value which should be used for XDCAMHD422
files?

best Regards
Christoph Gerstbauer


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