[opendtv] Re: News: Nielsen Gives Fuzzy Picture of HDTV Penetration
- From: "John Willkie" <johnwillkie@xxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 8 Nov 2007 13:04:30 -0800
Mark;
Good catch. In my experience, when reading from a file, ts_reader measures
these paramters in file time, not transport stream time, and it's quite fast
and reads transport streams from file faster than real-time.
So, I ran the KAKM stream through DtGrabber+ from Sencore/Dektec (which
measures in transport stream time)
Program 3 12.5 mb/sec. (video 12.3, audio .197)
Program 4 3.3 mb/sec (video 3.1, audio .197)
Program 4 2.26 mb/sec (video 2.06, audio .197)
I think I'm very busy on other things (having to do with timing in my psip
generator), but I decided to look at one of the transport stream captures
with Ts Reader again.
Aside from that, it's not clear to me where the bit rate value comes from in
Ts Reader. I looked at one of the streams with a 15 mb/sec bit rate, and I
didn't see the smoothing_buffer_descriptor anywhere. Perhaps it's derived
from the maximum for the level and profile.
It clearly shows a screen grab of program 4 on KCET as 16:9. The other two
I cited are shown as 4:3.
I have the ability to take a transport stream capture, output it via DVB-ASI
to a second machine and view and listen to it live with a variety of tools.
Unfortunately, at this moment, I'm not anywhere near to my second machine
and second DVB-ASI card.
With the exception of a few recent transport stream captures, I have looked
at every one of my transport stream captures using this setup.
Ts Reader costs about $200. DtGrabber plus the card it runs on costs more
than $2,000. Every tool has limitations. Not using tools, however, is much
worse.
John Willkie, who has seen a transport stream with two video services and
57% null packets.
-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Mark A. Aitken
Enviado el: Thursday, November 08, 2007 12:37 PM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: News: Nielsen Gives Fuzzy Picture of HDTV Penetration
Looking at your numbers, it is odd to see combined video bitrates for
program streams of the same station that (when added together) = more
than 19.39Mb/s. What's the deal there?
Not withstanding that oddity..15Mb/s for SDTV...what a waste !
John Willkie wrote:
> Here's the video parameters for program 2 on KAKM (PBS) in Anchorage as of
> 10/20/2007 at 06:50:54 gmt:
> MPEG Video: Bitrate 12.000 Mbps Resolution 704 x 480i
> MPEG Video: Framerate 29.97 fps Aspect Ratio 4:3 Chroma Format 4:2:0
>
> Here's the video paramters for program 3 on the KAKM, as of the same date
> and time:
> MPEG Video: Bitrate 12.000 Mbps Resolution 704 x 480i
> MPEG Video: Framerate 29.97 fps Aspect Ratio 4:3 Chroma Format 4:2:0
>
24Mb/s?
> Here's the video parameters for program 2 on KCET (PBS, LA) as of
10/26/2007
> 03:20:15 GMT
> MPEG Video: Bitrate 15.000 Mbps Resolution 704 x 480i
> MPEG Video: Framerate 29.97 fps Aspect Ratio 4:3 Chroma Format 4:2:0
>
> Same station, same time, program 3
> MPEG Video: Bitrate 15.000 Mbps Resolution 704 x 480i
> MPEG Video: Framerate 29.97 fps Aspect Ratio 4:3 Chroma Format 4:2:0
>
> Same station, same time, program 4
> MPEG Video: Bitrate 15.000 Mbps Resolution 704 x 480i
> MPEG Video: Framerate 29.97 fps Aspect Ratio 4:3 Chroma Format 4:2:0
>
45Mb/s?
--
Regards,
Mark A. Aitken
Director, Advanced Technology
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