Different recording formats by Channel? (1 Viewer)

[skoka123]

Hi mm,

I have uploaded two sample files (skoka123_HD_vs_SD.zip).

Yes it is a client server setup. One server and three clients. The specs I have mentioned in the first post belong to the Server.

Thanks,
Srikanth

 

[mm1352000]

Hi again

I've checked the samples and I can confirm they are *both* 1080i h.264 - I'd call that HD. The Times Now bitrate is stable at roughly 9.3 Mbps whereas the Star Movies bitrate varies quite widely between 4.5 and 8 Mbps. That would mean that a Star Movies recording could take significantly less HDD space than the Times Now recording, even though they are both 1080i h.264.

Getting back to what Tourettes said: if your clients all have roughly the same GPU capabilities as your server then there is no doubt you will need new hardware. Your server's GPU is does not support hardware accelerated h.264 decoding, and the 2.6 GHz Athlon CPU can't handle decoding by itself either if the bitrate is too high. Your best option is to get some relatively cheap video cards that support hardware accelerated decoding for each of the clients. For ATI I'd recommend no less than an HD 4670, 5450, or 6450.

mm

[Edit: you can use software like MediaInfo to examine the video details for recordings. VLC will also show some details in "Tools" -> "Codec Information".]

 

[skoka123]

Hi mm & Tourettes,

Sorry to trouble you once again. Please help me understand the problem a bit more in detail.

I would think if my GPU supports hardware encoding then it will also support hardware decoding. Am I wrong? Or is it possible that the the HDMI feed is simply being written to the disk without assistance from the GPU?

I do not think and cannot believe that the input stream from STB is all h.264 unless the STB is converting the MPEG2 SD to h.264. I say this because the satellite provider does not have enough bandwidth (transponder space) to add new MPEG4 channels or even simulcast in MPEG2 and MPEG4. They already have few millions of MPEG2 STBs already installed. All of us (MPEG2 & MPEG4 STB owners) point to the same satellites (Tata Sky on Insat 4A at 83.0°E - LyngSat).

This leads me to believe that the STB is upscaling the MPEG2 SD video content to h.264. I guess there will be some setting in the STB to prevent the upscaling.

Though MPEG2 consumes more space than MPEG4 I am certain that the actual bit rate used by my satellite provider will be much lower than the upscaled h.264 such that the overall disk utilized will be lower the the upscaled h.264.

You say that the video is h.264 then shouldn't it be recognized as one by Windows 7. Why does it show up as MPEG-2 in file properties in Windows Explorer. Does it point to some codec issues?

Coming to GPU capabilities, the GPU capabilities of the server is much below the capabilities of the client. As I do not have a spare pci-e slot the only option is probably to go for a new motherboard. Would an AMD Llano A8-3850 APU be good enough (Newegg.com - Suggested Products

If only I could get a Videoguard CAM I would have gone for a DVB-S2 card instead of the Colossus .

Once again thanks a lot for helping me understand the problem and fix it.

Thanks,
Srikanth

 

[mm1352000]

Hi Srikanth

I would think if my GPU supports hardware encoding then it will also support hardware decoding. Am I wrong?

Yes you are wrong. GPUs do not encode. Encoding is the process of converting one format into another, like converting an analog s-video signal into an MPEG 2 video stream so that it can be stored or manipulated in a PC. The Colossus can encode, but not the GPU. Your GPU does not support hardware accelerated h.264 decoding.

Or is it possible that the the HDMI feed is simply being written to the disk without assistance from the GPU?

Exactly - the GPU has nothing to do with the HDMI input feed.

I do not think and cannot believe that the input stream from STB is all h.264 unless the STB is converting the MPEG2 SD to h.264. I say this because the satellite provider does not have enough bandwidth (transponder space) to add new MPEG4 channels or even simulcast in MPEG2 and MPEG4.

Let us be clear: with the same number of bits you can store higher quality video with h.264. h.264 is generally used for HD because it takes less space than MPEG 2. I also agree that it is unlikely that the channels are all provided in h.264, but something is re-encoding to h.264. If I had to guess, I would say it is the Colossus.

This leads me to believe that the STB is upscaling the MPEG2 SD video content to h.264.

What you have called "upscaling" is re-encoding. Converting from MPEG 2 to h.264 is an encoding process. Upscaling is resampling the video resolution - for example, converting from 720x576 to 1920x1080.

Though MPEG2 consumes more space than MPEG4 I am certain that the actual bit rate used by my satellite provider will be much lower than the upscaled h.264 such that the overall disk utilized will be lower the the upscaled h.264.

That is possible if the Colossus is encoding the signal.

You say that the video is h.264 then shouldn't it be recognized as one by Windows 7. Why does it show up as MPEG-2 in file properties in Windows Explorer. Does it point to some codec issues?

I have no idea, but Windows is wrong. TS files are technically MPEG-2 [systems] transport stream files. MPEG 2 in that context is not the same as MPEG 2 video. Very confusing...

Coming to GPU capabilities, the GPU capabilities of the server is much below the capabilities of the client. As I do not have a spare pci-e slot the only option is probably to go for a new motherboard. Would an AMD Llano A8-3850 APU be good enough (Newegg.com - Suggested Products

Probably.

If only I could get a Videoguard CAM I would have gone for a DVB-S2 card instead of the Colossus .

I predict your server would still struggle in some cases. I think before you regret your Colossus purchase, try to adjust the quality settings on the "quality control" tab for the Colossus (in TV Server configuration):
1. Expand the TV Servers node.
2. Expand the TV Server node to show the device nodes.
3. Select the Colossus crossbar node.
4. Go to the quality control tab and click the "check" button to see if quality control is supported.

I don't guarantee that this will work, but it is at least worth a shot.

mm

 

[skoka123]

Hi mm,

I cannot tell you how thankful I am for your continued help. I am sorry that I am taking so much of your time on just supporting one MP user. I guess it is time to donate once again to MP .

I find that the 'Quality Control' is supported in my setup. What exactly should I try out? I set the recording Bitrate mode to VBR average. The custom settings is 50% value and 75% peak value. What is this for? What are the other parameters for?

Can you please point me to any documentation / forum thread where I can find details of this?

BTW, are these settings effective if I use 4TR as recorder plugin?

Thanks,
Srikanth

 

[Vasilich]

mm, sorry for my (probably stupid) question:
are you sure that MPEG2 or MPEG4 signal from STB can be transported over HDMI? afaik, HDMI allows transfer of uncompressed raw video only (similar to VGA, just in digital form) plus audio in digital form and some other data.

 

[mm1352000]

Hi again Srikanth

I find that the 'Quality Control' is supported in my setup. What exactly should I try out? I set the recording Bitrate mode to VBR average. The custom settings is 50% value and 75% peak value. What is this for? What are the other parameters for?

Can you please point me to any documentation / forum thread where I can find details of this?

It seems like these settings are not documented at all.
After quickly examining the code, I would say it works like this:

Constant bitrate mode: recordings made with constant bitrate - probably not ideal, but it is possible that variable bitrate modes are not supported.
Variable bitrate average mode: recordings made with variable bitrate. This is preferred for better quality-per-bit (efficiency).
Variable bitrate peak mode: same as variable bitrate average mode, except that the peak bitrate is constrained. Not all encoders support this

The quality presets for bitrate are as follows:
Portable = 20%
Low = 33%
Medium = 66%
High = 100%
Default = (existing value, whatever that happens to be)
Custom = (the value set in the "custom" "value" field)

The chosen bitrate sets the [constant] bitrate for constant bitrate mode, and the average bitrate for *both* variable bitrate modes.

If you choose variable bitrate peak mode then you can limit the peak bitrate. There are peak bitrates that correspond with each preset:
Portable = 45%
Low = 55%
Medium = 88%
High = 100%
Default = (existing value, whatever that happens to be)
Custom = (the value set in the "custom" "peak" field)

Note that variable and especially variable peak modes are not guaranteed to be supported by all encoders. TV Server logs should tell me what modes are supported. Further, I'm not actually sure that these settings will work correctly. Unfortunately I don't have a tuner that supports them (my analog tuners require software encoders) and I'm pretty sure they weren't tested when Colossus support was added (although I did add the code for setting the quality) so it will be interesting to see if they work.

BTW, are these settings effective if I use 4TR as recorder plugin?

They will work (assuming they work with the MediaPortal TV plugin) as long as you don't use the Argus TV Server. If you use Argus then I have no idea.

mm, sorry for my (probably stupid) question:
are you sure that MPEG2 or MPEG4 signal from STB can be transported over HDMI? afaik, HDMI allows transfer of uncompressed raw video only (similar to VGA, just in digital form) plus audio in digital form and some other data.

You're probably right. Rather it should be me who is feeling stupid! :sorry:

mm

[Edit: I should also note that the percentages are in terms of the encoder capabilities. Say for example, the encoder on your card is capable of encoding at between 1 and 15 Mbps. A setting of 50% for bitrate would set an effective value of (15 - 1) * 0.5 = 7 Mbps. The same applies to all percentages. Minimum and maximum bitrates should be printed in your logs.]

 

[rekenaar]

Thanks fot that mm!

I will copy your explantion to wiki over the weekend if someone has not done it by then.

 

[skoka123]

Hi mm,

Sorry I couldn't check the settings until now. Please find attached the log and MediaInfo output in text format.

If you see the TV.log file, you can see that the custom settings and VBR is working. The custom setting is 20% to 40% so the max bitrate should have been (20 - 1) * 40% = 7600 kbps. If you see both the MediaInfo files the bitrate is much higher than what I expected.

I would still like to explore any possible solution to my the original problem that of lower disk usage for SD Vs HD. I have not gone through all the 50+ pages of the HD-PVR/Colossus thread before I bought the Colossus. I assumed that the Audio and Video stream will be passed through bypassing the encoding process. Now that I read the FAQ on Hauppauge's website, I see that there is no escaping.

I was wondering if there is some way of adding a pre-recording command either in 4TR or TV-Server. If and when I want to record an SD channel set the bitrates lower and set it to high when recording HD. Is this something possible?

BTW, on an unrelated note, what exactly would I gain by using HDMI over Component if my STB outputs is 1080i and 720P. In either case the Colossus is going to encode the video so what is the big deal about support for HDMI? I am really confused. Did I fall for marketing jargon and hype.

Thanks,
Srikanth

 

[mm1352000]

Hi again Srikanth

If you see the TV.log file, you can see that the custom settings and VBR is working. The custom setting is 20% to 40% so the max bitrate should have been (20 - 1) * 40% = 7600 kbps. If you see both the MediaInfo files the bitrate is much higher than what I expected.

Yes, it does seem high. Have you tried CBR mode to see if the encoder adheres to the settings? VBR is much more difficult to check as the encoder will use higher bitrates for high motion scenes.

I would still like to explore any possible solution to my the original problem that of lower disk usage for SD Vs HD.

This is difficult from our perspective because your video is always arriving as h.264 - we can't automatically tell the difference between HD and SD.

I was wondering if there is some way of adding a pre-recording command either in 4TR or TV-Server. If and when I want to record an SD channel set the bitrates lower and set it to high when recording HD. Is this something possible?

My understanding is that it *may* be possible to set the bitrate on a per-recording basis. I have never tested this, but try:

1. Open MP.
2. Go to the TV section.
3. Click "scheduled".
4. Click "new" on the left.
5. Select "advanced record".
6. Select the channel.
7. Select the recording type (best to use "record once" for testing).
8. Select date, time and duration details.
9. Select the bitrate mode. Pick a different one from the playback and recording settings so that we can tell it really works.
10. Select the quality. Again, best to choose something different here.

Does that allow you to set the quality of each recording as you desire? Please provide logs to prove either way.

BTW, on an unrelated note, what exactly would I gain by using HDMI over Component if my STB outputs is 1080i and 720P. In either case the Colossus is going to encode the video so what is the big deal about support for HDMI? I am really confused. Did I fall for marketing jargon and hype.

The big deal is that HDMI is digital. There is no quality loss in the conversion (inside the STB) from digital to analog, and no loss in the cabling. Yes it is true the Colossus re-encodes, but theoretically it is better than doing two re-encodes (digital -> analog in STB to go to component/composite/s-video, analog -> digital in capture card).

mm