Hi All
I've been experimenting with some really low symbol (and thus video bit) rates.
What I'm finding, is that for any video bitrate under 100kbps, the MiniTioune (0.9beta8_9) software really struggles to decode it. The video is very choppy. Streaming the output from MiniTioune to an rPi running omxplayer or VLC, the video is generally very smooth. The rPi isn't cheating too much by using buffers, as its video isn't very out of sync with Minitioune
Sometimes, leaving Minitioune play the content for a few minutes will make it smooth.
Has anybody else experienced this?
Thanks
Jonny
Low bitrates
Re: Low bitrates
No. I have found it very stable. You need to enter the frequency accurately on mt and need to have the Low sr box ticked.
On the satellite qo100 I can easily decode 33 , 66 or 125 with ease.
This was much harder to do on previous versions of mt.
On the satellite qo100 I can easily decode 33 , 66 or 125 with ease.
This was much harder to do on previous versions of mt.
Re: Low bitrates
In my case, I don't believe this is a demodulation issue, as VLC plays the stream just fine. I think it is something specific with whatever decoder MiniTiouner uses for H264. It could actually be my computer, as I'm running OBS studio at the same time.
Cheers
Jonny
Cheers
Jonny
Re: Low bitrates
Hello,
This is because TS received is not DVB compliant.
Minitioune uses the Windows Mpeg2 demultiplexer, this demultiplexer is very sensitive to bad timing in the TS, as professional DVB receivers do.
As professional receivers, Windows Mpeg2 demultiplexer take care of timing of each elementary stream ( video, audio ...) to present them synchronized on screen and Loud speakers, (lip synch..)
if you test Minitioune with correct TS ( DVB compliant) you have no problem with the rendering.
The problem is with PCR, PTS and DTS that are most of time very bad in your TS. Send me 20sec of TS where you have "choppy" video and I will return you the analyze of TS that will shows all bad timing concerning PCR, PTS and DTS.
VLC act as standard receivers = it doesn't take care of timing for rendering ( but if you use the message_tool in VLC you will see many errors in your TS - set : tools=>message=>verbose =2)
so , using VLC, you can see a more fluid result ( but not always lip synch).
That's one reason why MiniTioune can send the TS to VLC,
so, as some other software do, you can use Minitioune always with VLC, not searching the PIDs with Minitioune and not showing the video at all inside Minitioune.
The other solution should be to verify your TS and transmit only DVB compliant TS.
If you receive the O-100 Beacon, the video displayed by Minitioune is not choppy because PCR, PTS, DTS timing are not bad.
I use also professional encoders at very low rate and have never issue with Minitioune video rendering.
Last cause could be your PC that is not powerful enough to do all jobs you ask at same time.
But I bet 99% on a poor DVB compliant TS.
the lower is the Symbol rate, more is difficult for the software to create a good timing inside the TS.
this is the biggest problem for developers.
Jean-Pierre F6DZP
This is because TS received is not DVB compliant.
Minitioune uses the Windows Mpeg2 demultiplexer, this demultiplexer is very sensitive to bad timing in the TS, as professional DVB receivers do.
As professional receivers, Windows Mpeg2 demultiplexer take care of timing of each elementary stream ( video, audio ...) to present them synchronized on screen and Loud speakers, (lip synch..)
if you test Minitioune with correct TS ( DVB compliant) you have no problem with the rendering.
The problem is with PCR, PTS and DTS that are most of time very bad in your TS. Send me 20sec of TS where you have "choppy" video and I will return you the analyze of TS that will shows all bad timing concerning PCR, PTS and DTS.
VLC act as standard receivers = it doesn't take care of timing for rendering ( but if you use the message_tool in VLC you will see many errors in your TS - set : tools=>message=>verbose =2)
so , using VLC, you can see a more fluid result ( but not always lip synch).
That's one reason why MiniTioune can send the TS to VLC,
so, as some other software do, you can use Minitioune always with VLC, not searching the PIDs with Minitioune and not showing the video at all inside Minitioune.
The other solution should be to verify your TS and transmit only DVB compliant TS.
If you receive the O-100 Beacon, the video displayed by Minitioune is not choppy because PCR, PTS, DTS timing are not bad.
I use also professional encoders at very low rate and have never issue with Minitioune video rendering.
Last cause could be your PC that is not powerful enough to do all jobs you ask at same time.
But I bet 99% on a poor DVB compliant TS.
the lower is the Symbol rate, more is difficult for the software to create a good timing inside the TS.
this is the biggest problem for developers.
Jean-Pierre F6DZP
Re: Low bitrates
Jonny
I would support Jean-Pierre. The TS that you are generating from a Portsdown with LimeSDR is not DVB-compliant, and it is totally wrong to assess MiniTioune's performance using Portsdown as a source.
In the same way as the AM TV transmitters that we used to build in the 1980s did not generate signals to broadcast standards, neither do our current (cheap in terms of broadcast equipment) self-build digital transmitters generate signals to broadcast standards. If you want that level of quality, you would need to pay many thousands of pounds, not just a few hundred.
Dave, G8GKQ
I would support Jean-Pierre. The TS that you are generating from a Portsdown with LimeSDR is not DVB-compliant, and it is totally wrong to assess MiniTioune's performance using Portsdown as a source.
In the same way as the AM TV transmitters that we used to build in the 1980s did not generate signals to broadcast standards, neither do our current (cheap in terms of broadcast equipment) self-build digital transmitters generate signals to broadcast standards. If you want that level of quality, you would need to pay many thousands of pounds, not just a few hundred.
Dave, G8GKQ
Re: Low bitrates
Jean-Pierre and Dave,
Thank for for your excellent explanation on DVB timing. I had no idea that Portsdown didn't generate a compliant DVB stream. This explanation makes sense to me.
So, in a nutshell, this is normal and to be expected for all Amateur-generated DATV content? Or are there any way to improve upon this (I guess use higher symbol rates?)
Thanks
Jonny
Thank for for your excellent explanation on DVB timing. I had no idea that Portsdown didn't generate a compliant DVB stream. This explanation makes sense to me.
So, in a nutshell, this is normal and to be expected for all Amateur-generated DATV content? Or are there any way to improve upon this (I guess use higher symbol rates?)
Thanks
Jonny