[FFmpeg-user] How to set 3 specific metadata flags (ITU601/displayoffset) in FFmpegs IMX50 MXF-OP1a encoding?

tim nicholson nichot20 at yahoo.com
Thu Mar 19 11:07:39 CET 2015

On 18/03/15 09:46, Christoph Gerstbauer wrote:
> Hello
> I am testing with ffmpeg the IMX50 D10 encoding, and I am very close to
> my target but I have to create 3 metadata values in the MXF header which
> is standard in most IMX50 MXF ecndodings:
> + display y offset = 32  - I am encoding 720x608 sources with included
> VBI area (32 lines high at the top) -> the offset 32 defines the active
> picture -> 720x576
> + Color siting = 4 (Rec 601)
> Is it possible to encoded with ffmpeg in a way that these values can be
> written?
> If yes, which syntax should I add to my used syntax?
> If no, could the option be implemented in future?
> My used ffmpeg syntax is:
> ffmpeg -i <inputfile> -map 0:v -map 0:a  -c:v mpeg2video -r 25 -pix_fmt
> yuv422p -aspect 4:3 -minrate 50000k -maxrate 50000k -b:v 50000k -intra
> -flags +ildct+ilme+low_delay -intra_vlc 1 -non_linear_quant 1 -ps 1
> -qmin 1 -qmax 3 -top 1 -dc 10 -bufsize 2000000 -rc_init_occupancy
> 2000000 -rc_buf_aggressivity 0.25 -tag:v mx5p -c:a pcm_s24le -ar 48000
> -f mxf_d10 <outpufile.mxf>

Don't know if its relevant but your coding parameters are slightly
different to the one's I use for D10, and I wonder if this affects the
automatic metadata insertion..

"-flags +ildct+ilme+low_delay"

Well ilme seems kind of redundant for I frame only coding but probably

"-tag:v mx5p"

irrelevant for mxf, but again probably harmless.

I use the following which you do not:-

-rc_max_vbv_use 1

-rc_min_vbv_use 1

and you use the following that I do not:-

"-qmax 3 -rc_buf_aggressivity 0.25"

I don't know what difference, if any, those changes make, but the values
I use create D10 files that BBC R&D looked at and thought were OK.

Perhaps worth a try?

> [..]

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