qustions about HD recordings and subchannels

[John Sparks]

I am getting ready to by an HDHomerun box and was doing preliminary research into HD recording and saw that BTV will record an entire HD channel with all subchannels, and that you can use streamsnip to get rid of the subchannels you didnt want to record.

My questions are, what if you WANT to use this "feature" to record multiple shows at once (you WANT those subchannels?)

1. Is there any way to "split" the recording into multiple MPEG2 (or divix) recordings, one for each subchannel?

2. or is there anyway to switch between the subchannels while you are watching the main recording in btv?

[tscales]

Nope and Nope, as far as I know.

I also don't believe the HDHomerun records the subchannels. I think it is the only HD tuner that does not.

Where I live, the subchannels are pretty unexciting. Weather radar, etc.

[Fonceur]

Originally Posted by John Sparks

I am getting ready to by an HDHomerun box and was doing preliminary research into HD recording and saw that BTV will record an entire HD channel with all subchannels, and that you can use streamsnip to get rid of the subchannels you didnt want to record.

Typically, for the HDHomeRun, the channel configuration only selects the appropriate sub-channel, so there is no point in running streamsnip on it. But otherwise, yes that is how it works for OTA with the other capture devices...

My questions are, what if you WANT to use this "feature" to record multiple shows at once (you WANT those subchannels?)

For the HDHR, you would select program 0, when setting up the channels, which basically says not to filter the sub-channels...

1. Is there any way to "split" the recording into multiple MPEG2 (or divix) recordings, one for each subchannel?

Yes, but not sure how easy it would be. You might be able to do that with VideoReDo, selecting a specific sub-channel and saving it to a file...

2. or is there anyway to switch between the subchannels while you are watching the main recording in btv?

I think it's the "[" and "]" keys...

[sswingle]

I believe HDtoMPEG can split the streams. While having never tried it, there is a drop down box in the program to select a stream.

[John Sparks]

thanks.

another dumb question. If I use the QAM tuner and my digital cable as my input, do those HD channels have subchannels or does the cable company split them into separate channels before HDHR even sees it?

Looking on Silicon dust's site there is a tool that lists the free qam channels in your zipcode.

One entry for my area looks like this:

qam256 72 1 WLKYDT 1920x1080i 16:9

qam256 72 2 WAVEDT 1920x1080i 16:9

qam256 72 5 WAVEDT 704x480i 4:3

Is that saying that the channel is 72 and the subchannels are 1, 2, 5?

Would that mean BTV would record all three channels at once? because if that is the case it would mean it was recording wlky (CBS) and wave (NBC) at the same time. That would be cool.

[Rich A]

Just a note regarding the content of the various sub channels. Here (using my OTA digital tuner) there are for example 1 major and 2 subchannels for the local CBS affiliate.

In some cases the primary and first sub channel actually have the same content but their contents air at different times. Also the first sub channel is digital but 480, whereas the primary is either 480 or 1080 depending on what they are sending.

For example, our CBS OTA primary channel has "Oprah" playing from 4 PM to 5 PM. But on its first secondary channel the same Oprah airs from 5 PM to 6 PM. The third digital stream shows 24 hour weather.

That same primary OTA content is also on my clear QAM channel BUT both the secondary channels are not being broadcast. I wondered why my OTA one hour show was usually about 8 GB long and the same OTA one hour show via digital cable was around 5 GB.

I suppose having the delayed one hour Oprah might be useful if the primary feed was in conflict with something OR you were watching live TV and missed the 4 PM show. Not that I ever watch Oprah of course.

[Fonceur]

Originally Posted by John Sparks

Is that saying that the channel is 72 and the subchannels are 1, 2, 5?

Yes, if you setup the channels to use the program 0 instead of 1, 2 and 5, you would be getting the full unfiltered stream.

BTW, squeezing a SD channel with 2 HD channels in the same QAM means that you are getting a lower bit rate for your HD channels. Do you know if the stations are using sub-channels for the OTA transmission or if it's the cable company that is limiting the bit rate to cram more channels?

[Nick Burns]

I thought that the HDHomerun only recorded the selected channel too and none of the subchannels, but I just did a StreamSnip on a show recorded from the HDHR and it went from 9.6GB to 5.6GB, so it's got to be getting rid of "something".

[nanook105]

Originally Posted by Nick Burns

I thought that the HDHomerun only recorded the selected channel too and none of the subchannels, but I just did a StreamSnip on a show recorded from the HDHR and it went from 9.6GB to 5.6GB, so it's got to be getting rid of "something".

Are you recording OTA or QAM. OTA has the subchannels

[Nick Burns]

OK... that explains it then.

[John Sparks]

Originally Posted by Fonceur

Yes, if you setup the channels to use the program 0 instead of 1, 2 and 5, you would be getting the full unfiltered stream.

BTW, squeezing a SD channel with 2 HD channels in the same QAM means that you are getting a lower bit rate for your HD channels. Do you know if the stations are using sub-channels for the OTA transmission or if it's the cable company that is limiting the bit rate to cram more channels?

I think its the cable company. cuz the subchannels I listed above on the cable are two entirely different networks (cbs and nbc)

I just ordered the HDHR, I guess I will figure it all out when I get it.

[Fonceur]

Originally Posted by John Sparks

I think its the cable company. cuz the subchannels I listed above on the cable are two entirely different networks (cbs and nbc)

Actually, I did mean the original cbs and nbc ATSC transmissions...