[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 16:39:29 CET 2015

On 19/03/15 13:38, Christoph Gerstbauer wrote:
>> 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
>> harmless.
>> "-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?
>>> [..]
> Additionally:
> I tried it again with all your mentioned syntax changes but without
> changing the "-qmin 1 -qmax 3" -> now it works to encode.
> But the MXF metadata doesnt change (SIGNAL STANDARD = 1 (ITU 601) +
> display y offset +Color siting = 4 (Rec 601).
> The only difference I saw with mediainfo is that the new MXF (your
> syntax) has a CLOSED GOP structure and the old one (my syntax) had a
> OPEN structure.
> Best Regards
> Christoph
> [..]

Shame, don't understand the qmax issue. but if you look at:-

tests/lavf_regression.sh line 90

you will see an IMX30 example which uses -qmax 12 and my other other
parameters. However not sure what difference closed/open gop makes on I
frame only, but being purist I can see how you might want to set closed
gop! S356m makes no reference to it that I can see.

Looks like we might need a patch for what you want.

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