On 22.11.2017 23:52, Carl Eugen Hoyos wrote:
2017-11-22 16:41 GMT+01:00 Tobias Rapp <t.r...@noa-archive.com>:
Writes one set of field framing information for progressive streams and
two sets for interlaced streams. Fixes ticket #6383.

Unfortunately the OpenDML v1.02 document is not very specific what value
to use for start_line when frame data is not coming from a capturing
device, so this is just using 0/1 depending on the field order as a
best-effort guess.

I believe your approach is sane but the only available examples
may indicate that it should be set to something like height / 2 ;-(

Indeed my main problem is that I have not found some real-world example file with two sets of field framing information. I scanned the files at http://streams.videolan.org/samples/ but out of >900 AVI files only about 40 files contain a vprp chunk but none contains two fields.

I have found two files that have FieldPerFrame=2 (indicating an interlaced video stream) but they contain a truncated vprp chunk (no field framing information):

As this clearly doesn't match the specs I didn't want to follow these two examples.

I can use height/2 for start_line offset instead of 1 if that sounds better, to me it would look like an indication that the fields are stored separated, but no strong opinion from my side.


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