00:59 <programmerjake> Hi, I'm thinking of working on the .mcc decoder and was wondering if you think I should add an option to convert between 30fps and 29.97fps inside the decoder, because for some reason other programs like to use the wrong fps when creating .mcc files, e.g. I have a 30fps .mcc that corresponds to a 29.97fps .mp4. to be clear the conversion would be

00:59 <programmerjake> making the file duration change, not duplicating/dropping packets.

01:01 <programmerjake> I did try using the setts bitstream filter but it's definitely not intuitive and tbh I'm still not sure I got it to work correctly, whereas changing that in the demuxer itself would be trivial

01:02 <programmerjake> *relatively trivial

01:48 <Lynne> no, output exactly what's in the file

01:48 <Lynne> use setpts if you want to convert

01:48 <Lynne> or a bitstream filter to change properties

01:58 <programmerjake> ok, what about adding an option to make it output the full vanc data instead of the EIA-608 captions data? or just make it only output vanc data and add a bitstream filter to extract EIA-608 captions data? does ffmpeg allow auto-inserting bitstream filters on the demux side?

02:00 <programmerjake> as mentioned on the mailing list, I think adding a new codec id for mxf vbi vanc smpte 436m could work for having a common vanc format in ffmpeg

02:01 <programmerjake> also, does ffmpeg support chaining multiple bitstream filters? or would I need to have a merged change fps and decode vanc filter?

02:08 <programmerjake> seems as though it does support chaining at least in the ffmpeg tools, though afaict it only supports one filter per stream with ff_stream_add_bitstream_filter

02:10 <Lynne> yes, you can specify multiple filters as -bsf:v filt1,filt2 etc.

02:11 <programmerjake> ff_stream_add_bitstream_filter has av_assert0(!sti->bsfc); so unless I'm missing something you can't add multiple filters per stream from a muxer

02:13 <Lynne> why would you want to apply a setts from a muxer?

02:15 <programmerjake> idk, maybe if there's also a video stream or something where you know what frame rate the output should be but the vanc stream has the wrong framerate because apparently the standard says you can ignore the difference between 30fps and 29.97fps for vanc (seems very shortsighted to me)

02:15 <programmerjake> and you also need another filter for format conversion

02:16 <programmerjake> (i'm also working on a .mcc encoder in case you were wondering)

02:17 <programmerjake> in the .mcc encoder, so far I haven't figured out a reliable way to get the actual frame rate of the input, seems like everything other than time_base isn't actually set before calling write_header

02:18 <programmerjake> so for now I just added an option to select your own frame rate

02:18 <Lynne> if you're a muxer you can literally just alter the timestamps directly

02:18 <programmerjake> guess that's true...

02:20 <programmerjake> I do also want to get .mcc input to mux into a .mxf file...

02:22 <programmerjake> would adding the new codec id for mxf vbi vanc smpte 436m and then changing the mxf decoder/encoder to use that new codec id instead of AV_CODEC_ID_NONE be considered a breaking change that needs a major version bump?

02:32 <Lynne> not according to me

02:35 <programmerjake> k, thx!

03:37 <Lynne> ePirat: could you decode a single frame from https://files.lynne.ee/P1000520.MOV and https://files.lynne.ee/P1000521.MOV ?

03:38 <Lynne> or maybe all of them, there are only a few frames there and it would help to average out

03:41 <Lynne> same input, prores raw vs prores raw hq, if we know the difference between quantized coeffs for each and dequantized coeffs, then it should be possible to figure out the dequant method

07:24 <fflogger> [newticket] rabcor: Ticket #11665 ([undetermined] Input pattern recognition broken when using avif format) created https://trac.ffmpeg.org/ticket/11665