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[dennismf]

I recently downloaded MC13.0.95 and configured it to receive and record DVB-T transmissions.

I use AC3Filter to send ac3 and dts audio to my audio receiver via SPDIF passthrough. I have tried a number of different codecs (including alternate audio codecs with spdif passthrough capability) but all seemed to suffer from the following problems. My current config uses AC3Filter and the Cyberlink video decoder that comes with PowerDVD 8. I use Windows Vista Home Premium SP1.

I am experiencing a problem with ac3 audio, SPDIF passthrough and MC13 recording files. I have experimented with various configurations with the following results:-

1. If I watch live DVB-T material without activating timeshifting, no audio problems occur. AC3Filter behaves as I would expect, sending ac3 audio via passthrough and decoding mpa audio for standard stereo output via SPDIF.

2. If I activate timeshift while watching a program with mpa audio (no SPDIF passthrough), timeshifting seems to work. If I switch to a program with ac3 audio, timeshifting continues to work and AC3Filter appears to change to use the mpa audio stream within the program that is configured to deliver deliver ac3 audio (most Australian DVB-T progams offer both mpa and ac3 audio).

3. If I activate timeshift while watching a program with ac3 audio (SPDIF passthrough), I loose the audio (picture but no audio). Changing to other mpa audio programs still delivers no audio. Audio is restored when I exit from timeshift mode.

4. If I record an ac3 audio program with MC13, when I play it back with SPDIF ac3 passthrough, there is no audio. Although AC3Filter reports normal passthrough activity (status, audio frame count etc). If I turn off ac3 passthrough in AC3Filter, audio is restored.

I am a long time user of MC. I currently use Microsoft MC in Vista to watch live DVB-T material. I would like to shift this the MC but cannot do this until timeshift playback becomes stable in my environment. If you are still with me here, thanks for reading my story. I am happy to participate in any diagnostic work that may assist in identifying the cause of this problem.

Happy new year - Well it's new year in Australa now.

[JimH]

Happy New Year, Australia.  You might also post a link to this thread on the TV board here so that Yaobing sees it.

[dennismf]

I have placed a link to this under "TV Cards and TVs".

I have now installed 13.0.100. The above behaviour still occurs. However I noticed that timeshift works correctly with ac3 SPDIF passthrough when I only tune to HD programs. The only audio difference I am aware of with Australian HDTV is that ac3 is the default audio. If I start timeshifting on an HD program and switch to a non HD ac3 program, I loose the audio. When I switch back to an HD program, ac3 passthrough audio is restored ?

[jmone]

Hi Dennis this as been an on and off issues for awhile.  To summarise, if you switch between DVB-T channels that have different audio streams eg MPEG / DD audio you sometimes lose the Audio.  You can get the audio back by stopping and starting playback of the TV Station again.

[raym]

Hi there. I have experienced these problems myself and there's a recent thread by "imugli" about this here: http://yabb.jriver.com/interact/index.php?topic=49692.0

[bold below added by JimH]
What you need to do is make sure you enable the AC3 Encode option in AC3Filter (on the main page). I know this is not strictly passthru but by allowing AC3Filter to "re-package" all streams (mpa and AC3) into a "new" AC3 stream (before sending it to your amp over spdif) seems to fix the issue - regardless of your Timeshifting setting. By doing this, you can also take advantage of some of this codec's advanced post-processing features like normalisation which is particularly useful for taming audio levels irrespective of the audio type used between programs and channels.

I'm using XP currently but from memory, this work's fine under Vista too.

I think this is probably an MC bug but as you've said, most Australian DVB-T progams offer both mpa and ac3 audio which is somewhat unique. ATSC TV streams are all AC3 (I believe) so others will probably never experience the issue.

Anyway, let me know if you continue to have problems but the above works for me!

Happy New Year, Australia. 

Happy New Year to you Jim and everyone at JRiver!!

[Yaobing]

Nathan and Ralf,

Thanks for helping your fellow Australian.

Happy New Year to you all.

Yaobing

[dennismf]

Thankyou for the prompt replies. I will try out the suggestions.

Cheers