[robert]

Hey Matt!

Thank you for the great MXFLib!

I have a short question: Is there a possibility to write small parts of the MXF-Body and all ending up in a single partition using the Bodywriter?

The reason for the question is that i would like to abort the writing upon user request. The code should look like (Writer is of class BodyWriter):

Code:

// End header partition
Writer->EndPartition();

while (!Writer->BodyDone()) {
    // write a couple of edit units
    Writer->WritePartition(50,0);

    // check if user wants to abort
    .....
 }

instead of just

Code:

Writer->WriteBody();

which puts everything in one large partition but can take a while to finish. From the documentation and the code in essence.cpp I assume propably yes but I managed to do it only with changes to BodyWriter::WriteEssence and that doesn't seem right

Also: I probably overlook some special case, but shouldn't line 2597 in essence.cpp rather be:

Code:

if(ThisSize >= RemainingDuration)

Otherwise always one more edit unit is written than in the WritePartition-Call specified?

Thank you,
best regards,
Robert

[Matt Beard]

The +1 thing is (if my memory serves me correctly) because the last edit unit is stored for next time a body partition is started.

I do like the idea of being able to cancel a write part way through, but this would be quite difficult to make work from within the BodyWriter for clip-wrapping as it passes the entire clip (or details of it!) down to a lower level.

My recommendation would be to write a version of EssenceSource that works as a "filter", passing calls to all methods through to another essence source, but with a hook in GetEssenceDataSize, GetEssenceData and EndOfData to flag that the essence has ended if a test shows that the cancel button has been pressed.

Then rather than:

Code:

BodyStreamPtr MyStream = new BodyStream(OriginalSource);

... you do:

Code:

EssenceSourcePtr NewSource = new FilterSource(OriginalSource);
BodyStreamPtr MyStream = new BodyStream(NewSource);