Re: Lightweight Editing using GMFBridge

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Bob wrote:
I'm using GMFBridge as a lightweight alternative to DES; I couldn't
keep DES from decompressing and recompressing DV video. I've changed
the output side of Geraint Davies GMFPlay sample to write to a file.
The object is to combine clips to a standard formatted AVI. It
optionally transcodes them to WMV. I build two versions of the output
side; one for DV video in AVI files, one for WMV files.

I ran into trouble with audio/video sync. The audio stream runs right
through and winds up concentrated at the beginning of the file. I
detected this with Media Player Classic, which puts up a graphic when
the interleaving is out of whack.

I fixed this for AVI output by calling SetSyncSource on both the input
and output graphs with the System Reference Clock. The AVI MUX on the
output side seems to fix things, given a reference clock.

Here are my graphs:

The DVSD filter is an in-place transform filter that insists on DVSD
input and output. Without it, Intelligent connect inserts the DV
decompressor filter between the splitter and the Bridge Sink.

Intelligent Connect inserts the ACM wrapper. The splitter won't connect
directly to the sink filter. It's the buffering.

The input graph is the same whether I'm writing to AVI or WMV.

file reader -> AVI Splitter -> DVSD -> Bridge Sink filter
ACM Wrapper ->

Bridge Source filter -> AVI Mux -> File Writer
->

Setting the Sync Source didn't work with WMV output.

Bridge Source filter -> DV Video Decoder -> ASF File Writer
--------------------->

My question is this. How can I get audio and video back in sync when
writing to the WMV? What am I missing here?

Thanks!
Bob

With some more checking, I find that Media Player Classic reports the
audio chunks are evenly distributed through the first *two thirds* of
the file. They are still out of sync.

How can I get GMFBridge to preserve audio/video sync?

.

Relevant Pages

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