Comcast digital cable

[cnelson87]

I'm in the So. Seattle area and have Comcast digital cable with the Motorola 6412 DVR box. I'm using Firewire out to record the pure digital stream to my Mac (this is well documented, no need to go into it here). However, these "pure digital streams" really kinda suck! The mpg2 streams are a weird resolution 528x480 (not a surprise to me, it's been mentioned in a previous thread) and, in the little testing I've done so far, they seem to be full of data errors. I was hoping to be able to keep the original ac3 audio intact but there are too many data breaks. MPEG Streamclip does a pretty good job of exporting to mpeg but not perfect. I'm seeing weird coloration fluctuations intermintently and heavy pixelation during scene transition-fades.
Just making an observation, I guess I don't really have a question unless maybe to ask if anyone else sees this too and how they deal with it. I would like to clean these vids up and export to some kind of mpg4 and maybe DVD compliant mpg2 for archiving.

[Frobozz]

You can get the 528x480 digital channel streams still? In Eugene Comcast has 5c protected all but the Network HD channels and the analog channels. And nobody would want to keep the lousy MPEG encoding the 6412 does of the analog channels. I haven't been able to capture the other digital channels to my Mac for months.

But back to your issue. Even when I could extract those streams and use Streamclip to create MPEGs I didn't like the result as well as using my Pioneer standalone DVD recorder to record from the 6412's S-video output. It seems the 6412 knows well what to do with those poor quality streams.

[edDV]

You can get the 528x480 digital channel streams still? In Eugene Comcast has 5c protected all but the Network HD channels and the analog channels. And nobody would want to keep the lousy MPEG encoding the 6412 does of the analog channels. I haven't been able to capture the other digital channels to my Mac for months.

Same here in N.California except they protected every channel except the DTV locals. The 528x480 "digital MPeg2" channels aren't worth the bother anyway. I only IEEE-1394 cap the local HD TS output @ Comcast's 25Mb/s data rate.

But back to your issue. Even when I could extract those streams and use Streamclip to create MPEGs I didn't like the result as well as using my Pioneer standalone DVD recorder to record from the 6412's S-video output. It seems the 6412 knows well what to do with those poor quality streams.

I use my Canpopus ADVC-100 to cap from the S-Video output to my home built PVR. I also use an ATI based 550 tuner to realtime MPeg2 cap the analog channels or the S-Video for SD and HD digital channels. The HD to letterbox SD MPeg2 looks quite good through either path. Quality in means quality out.

[cnelson87]

I just started getting the 528x480 digital streams last week. Previously, I assumed most shows were analog and the DVR encoded to mpeg2 720x480 7500mbps, 48kHz ac3 2.0 audio(sometimes 32kHz, weird...). Now, the live video does seem to look better (but jeez these mpgs suck!) and the audio is consistently 48, but the bitrate is much lower.
Would 5c protection make the mpg completely scrambled and unwatchable, or just mess with the pixelation and colors (and my head)?
Botttom line, most TV shows suck and Comcast just raised my rates so I'll be dropping it soon anyway. Thanks for your responses.

[Frobozz]

Depending on the area, Comcast has started digital simulcasts of its analog channels, so that may be what you're getting now. It should be an improvement over the analog picture. If you do have the digital simulcast and wanted to stay with Comcast you maybe could trade your 6412 for a new 3412 that has no MPEG encoder.

What the 5c protection does is simply prevent any transmission from the 6412 to the Mac. When clicking record with VirtualDVHS2 no time ticks off the display. The unprotected network HD channels transmit with no problem. The analog channels also transmit in their 720x480 resolution but look awful.

The only reason I ever bother with this is the rare time when I want to create a 16:9 video DVD from a network HD program. I capture with VirtualDVHS2; edit out commercials and convert the TS stream to HD MPEG with MPEG Streamclip; and use Toast to encode, author and burn a 16:9 SD video DVD that retains the original AC-3 audio.

[edDV]

My neighborhood had a 750MHz Comcast upgrade last spring and in recent months they have tuned it up for quite good quality. Things got substantially better when they got rid of our local dish farm and brought the "digital" 528x480 SD and 20-25MBps HDTV channels in by fiber including the locals.

From March to July I was getting all the channels as IEEE-1394 MPeg2 TS streams but one day that all stopped with the exception of the DTV locals*.

I still get the in-box analog to 720x480 MPeg2 TS streams @7.5 Mbps but the quality is bad through the Motorola 6xxx compared to my other tuners (Philips HDTV analog tuner and ATI 550 tuner).

*The FCC ruled that cable companies can't scramble the locals but the individual DTV stations are free to do so as they see fit.

[edDV]

Depending on the area, Comcast has started digital simulcasts of its analog channels, so that may be what you're getting now. It should be an improvement over the analog picture. If you do have the digital simulcast and wanted to stay with Comcast you maybe could trade your 6412 for a new 3412 that has no MPEG encoder.

Comcast has decided to do this to provide a parallel quality progressive representation of the analog channels to the LCD and plasma class tv sets that can't properly tune and deinterlace analog. I'm sorry to see them chew up bandwidth this way. I'd rather see more HDTV channels.

Their long term goal is to get rid of analog and force every set to a set top box (like Dish and DirecTV). For me this removes the main advantage of cable. That is the ability to have multiple analog tuners without need of a box. This may drive me to sat to get my HDTV.

What the 5c protection does is simply prevent any transmission from the 6412 to the Mac. When clicking record with VirtualDVHS2 no time ticks off the display. The unprotected network HD channels transmit with no problem. The analog channels also transmit in their 720x480 resolution but look awful.

awful they are

The only reason I ever bother with this is the rare time when I want to create a 16:9 video DVD from a network HD program. I capture with VirtualDVHS2; edit out commercials and convert the TS stream to HD MPEG with MPEG Streamclip; and use Toast to encode, author and burn a 16:9 SD video DVD that retains the original AC-3 audio.

While the HD TS stream can look great, it takes forever to edit these things to a DVD. I only use TS for short clips. You can fit about 20-30 min of raw HD TS to a DVD as data for time shift.

Normally I capture the HD broadcasts from the letterboxed S-Video output for PVR use.

[Frobozz]

While the HD TS stream can look great, it takes forever to edit these things to a DVD. I only use TS for short clips. You can fit about 30 min of raw HD TS to a DVD for time shift.

Normally I capture the HD broadcasts from the letterboxed S-Video output for PVR use.

Me too. I did get a nice result, though, with the recent Elton John Las Vegas concert. Plus there is the novelty factor of having pulled it off.

[AntnyMD]

You should switch your S-Video out on the 6412 to 16:9. This way you can use your standalone DVD recorder to record widescreen DVDs. You wont retain 5.1 surround sound, but you can make the DVD a lot faster than letting Toast convert for you. Editing HD MPEG2 on my Powerbook is way too frustrating right now.

The 5C protected channels are also encoded with Macrovision on the analog (S-Video) outputs. I bought an $80 filter to get past this.

[Frobozz]

AntnyMD, the Motorola 6412 does not have an option for 16:9 480i on any output. It only letterboxes. The good news is there is no Macrovision with the 6412's 480i that I've seen.

[edDV]

AntnyMD, the Motorola 6412 does not have an option for 16:9 480i on any output. It only letterboxes. The good news is there is no Macrovision with the 6412's 480i that I've seen.

I have the same experience with the Comcast Motorola box. I have the HD outputs set for 16:9 but the S-Video is always letterboxed. Usually I just make a letterbox DVD and rely on the DVD player or HDTV to scale up the 16:9. Often these DVDs are viewed on a 4:3 monitor.

[AntnyMD]

Guys guys forgive me, youre totally correct. I have my digital output from the 6412 routed through my JVC D-VHS machine via Firewire, and the D-VHS machine does not force letterboxing.