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ASF (WMV) recording

ASF (WMV) Recording

It may be necessary to install the "Windows Media Encoder 9 Series" pack, otherwise the recording may fail to start.

Overview The Windows Media (WMV) recording is enabled when RecordingMethod = rm_ASF, starts by invoking StartRecording, and stop by invoking StopRecording.

In this format video and audio compression are automatically performed on the fly by the current Windows Media encoder, therefore it is not necessary to specify the video compressors and/or audio compressors, they will be ignored.

The video and audio streams are recorded when AudioRecording is enabled, otherwise by default only the video stream is recorded.

Choosing the WMV8 or WMV9 encoding format By default the recording is made by using the WMV8 encoders (ASFProfileVersion = apv_ProfileVersion_8).

To record by using the Windows media 9 format and profiles set ASFProfileVersion = apv_ProfileVersion_9.

Live network streaming during the WMV recording It is possible to perform live network streaming during the WMV recording, according to the NetworkStreaming property: - directly to the network when NetworkStreaming = ns_ASFDirectNetworkStreaming - or to a Window Media Server when NetworkStreaming = ns_ASFStreamingToPublishingPoint.

Be sure that live network streaming is disabled if it is not required during ASF recording (NetworkStreaming = ns_Disabled).

Using profiles in WMV 8 format When recording in WMV8 format s (ASFProfileVersion = apv_ProfileVersion_8), it is possible to reuse one of the WMV8 predefined formats.

If ASFProfile = -1, the default ASF recording format is used. In this case the ASF... settings can be applied (see ASF recording properties below), the most critical is the ASFVideoBitRate, that defines the size of the clip and the level of compression. It is possible to make tests with different values to determine the best compression level for the app, e.g. start testing ASFVideoBitRate = 300000 and ASFVideoBitRate = 1500000, then it is possible to try values between or around theses values.

Otherwise a recording format can be chosen in the ASFProfiles list by assigning its index to ASFProfile, in a 0 to ASFProfilesCount - 1 range.

Note: be sure the general ASF properties below are set to "-1", otherwise they supersede the standard profile values. Using profiles in the WMV 9 format When recording in WMV9 format s (ASFProfileVersion = apv_ProfileVersion_9), it is possible to specify the audio/video encoding settings in a custom profile contained in a ".prx" file. Proceed as follows:

  • run the Windows Media Profile Editor (WMProEdt.exe), and modify or create a custom profile, then save it to a ".prx" file
  • assign the ".prx" file to the ASFProfileFromCustomFile property.

Note: be sure the general ASFVideo... and ASFAudio... properties below are set to "-1", otherwise they supersede the custom profile values. ASF recording properties The following ASF properties supersede the ASF profiles values when they values are <> -1: ASFVideoWidth ASFVideoHeight ASFVideoBitRate ASFVideoMaxKeyFrameSpacing ASFVideoQuality ASFBufferWindow ASFAudioBitRate ASFAudioChannels

ASF safe recording even upon power outage See Recording recovery after power outage