We have developed an AMA plug-in for adding DV, IMX and DNxHD files for editing as they are being capture. 

For the most part the process works fine, however we have encountered a slight problem when the file being captured is stopped prior to the originally selected duration. The issue is that the instance within the BIN (added as the clip is growing) reports the original (anticipated) duration even when the file is stopped early. Our capture solution updated the duration within the MXF but the corrected duration is not reflected in the instance within the BIN. If this same file is added to the BIN after capture is completed the new instance shows the corrected duration.

My question is whether there is a method of refreshing the duration of a clip if the actual duration has been updated after it was added to the BIN.

Any advice or assistance is very much appreciated.

-Bill Harris

Telestream, Inc.

Hi Bill,

>The issue is that the instance within the BIN (added as the clip is growing) reports the original (anticipated) duration

Media Composer requires that the full length of the essence be accessible at the time that the file is AMA-linked.   Based on your description, your plug-in violates that requirement, meaning that it is possible for a customer to AMA-link to an in-progress file, and will get a error if they try to play beyond the currently available media.

In the upcoming weeks Avid will be making an AMA plug-in Validation tool available to our AMA development partners.   If all the samples are not available when the file is AMA-linked, the AMA plug-in will not pass validation.

A rudimentary form of frame-chase support is available and documented in the amasdk documentation (pasted below).   More flexible frame-chase support is under consideration for a future release of the AMASDK.

FrameChase support in AMA

9.1 Overview

AMA plug-ins can mark a clip as "in progress" by adding the "_INPROGRESS_AMA" attribute
to the master mob with a value of 1.

mastermob->AppendAttribute(L"_INPROGRESS_AMA", L"1" ));

The plug-in is responsible for reporting a clip length limited to the currently available essence. It
must not report a clip length exceeding the media that is immediately available to play.

9.2 Presentation of Functionality in MediaComposer, NewsCutter and Symphony

AMA FrameChase is supported in MediaComposer beginning with version 6.5.
When the editor links to a clip that was reported as an "in-progress" clip by the AMA plug-in, it
appears in the bin with a special AMA FrameChase icon. In-progress clips can be refreshed using
the "Refresh in-progress AMA clips" command on the Bin menu. Once the clip is no longer in
progress, the next refresh will update the clips icon from the AMA FrameChase icon to a normal
AMA clip icon.

Each time the clip is refreshed, a new IMediaContainer interface is instantiated, so the plug-in must
not assume that state information will be preserved in the plug-in across the refresh operations.