Rank: Advanced Member
Groups: Registered
Joined: 1/29/2017(UTC) Posts: 140   Location: Squamish Thanks: 54 times
Was thanked: 4 time(s) in 3 post(s)
|
I am about to switch from Wirecast to vMix (wish I had done so earlier!)
However I noticed one issue with vMix - the quality of the fade transition is significantly poor compared to that seen in Wirecast 6.x
The fade transition in vMix (500ms) is extremely smooth when viewed in the program, but on the live webcast screen it looks blocky and 'pixellated'. This is not happening in Wirecast - same computer, same CDN, same bitrate settings, etc.
Can anyone suggest a cause and hopefully a solution?
Thanks...
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 3/20/2014(UTC) Posts: 2,721  Location: Bordeaux, France Thanks: 243 times
Was thanked: 794 time(s) in 589 post(s)
|
Can you give us more details:
- bitrate ?
- resolution ?
- encoder settings ?
- machine config ?
I have never noticed such a problem, unless my bitrate/bandwidth was too weak.
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 1/29/2017(UTC) Posts: 140 Location: Squamish Thanks: 54 times
Was thanked: 4 time(s) in 3 post(s)
|
The machine is a Lenovo thinkpad W530 - i7 quad CPU 8GB ram dedicated nVidia graphics card gigabit ethernet;
Bitrate 600 kbps video and 96 kbps audio
Standard def 720X480 NTSC
H264 encoding 29.97 fps
Application FFMPEG (should I switch to FMLE?)
Profile: Baseline
Level 3.1
Preset: very fast
Keyframe frq: 2 sec.
Threads: 4
Network Buffer: 20 sec.
Strict CBR (should I turn that off and go VBR?)
Not keyframe aligned.
Wired high-speed ethernet connection - 150 mbps for both upload and download.
Thanks.
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 3/20/2014(UTC) Posts: 2,721 Location: Bordeaux, France Thanks: 243 times
Was thanked: 794 time(s) in 589 post(s)
|
600 kbps is a minimal value for 480p. Try increasing this if you can. 1Mbps or even 2 (as you have the bandwidth available) it helps a lot. Don't know which CDN you use but for example YouTube recommends up to 2000 kbps for 480p
FFMPEG is ok but did you use hardware encoder?
For the encoding setting I think you don't need to save up CPU/GPU power, so try PRESET=FAST or even better
Also profile=MAIN (unless your CDN recommends not to)
Strict CBR is fine...
Keep us posted and don't hesitate to make tests... It's the best way to find the perfect settings
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 1/29/2017(UTC) Posts: 140 Location: Squamish Thanks: 54 times
Was thanked: 4 time(s) in 3 post(s)
|
Hi DWAM,
I am forced to keep the bitrate this low because my client's viewing audience always complains of having trouble with anything higher - they all seem to have Really slow connections and keep complaining of freezes if its higher(!)
I use MetaCDN (Streamshark)
This combination has always worked well when using Wirecast though which is what got me thinking...
I tested with and without the Hardware Encoder with no appreciable improvement.
I'll test with the other presets (fast, ultrafast, etc.) and profiles and let you know.
Thanks,
Pesi
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 3/20/2014(UTC) Posts: 2,721 Location: Bordeaux, France Thanks: 243 times
Was thanked: 794 time(s) in 589 post(s)
|
Quote:I'll test with the other presets (fast, ultrafast, etc.) the faster, the worse... remember
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 1/29/2017(UTC) Posts: 140 Location: Squamish Thanks: 54 times
Was thanked: 4 time(s) in 3 post(s)
|
Oh... good to know. thanks!
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 1/29/2017(UTC) Posts: 140 Location: Squamish Thanks: 54 times
Was thanked: 4 time(s) in 3 post(s)
|
Switching from Baseline to Main seems to have improved the image quite a bit - still some residual pixellation though but nowhere near as bad.
What are the Video 'level' - ie. 3.1 etc. about - should they be a possible cause?
Thanks
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 3/20/2014(UTC) Posts: 2,721 Location: Bordeaux, France Thanks: 243 times
Was thanked: 794 time(s) in 589 post(s)
|
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 1/29/2017(UTC) Posts: 140 Location: Squamish Thanks: 54 times
Was thanked: 4 time(s) in 3 post(s)
|
Been playing with settings and came up with these changes which seem to have helped...
1. Using the Main or High profile helps – is there any downside to using the High profile?
2. I reset the Level drastically to 1.1 from 3.1 – is this a factor? Can it cause problems for viewers/stream providers?
3. Set the Preset to Very Slow – is this a problem? Which gives better quality – Very Slow or UltraFast?
4. What effect will changing the Threads have? Should one increase it from 4?
Also when adding a camera input (I am using SD NTSC cameras connecting through Firewire inputs into the laptop)…
1. Should the Input be set as DVI or Composite?
2. What should the Video Format be set as? The default is UYVY but should it be changed to something else like H264 (since that is what I am streaming as) or maybe something else like RGB24/32?
Any advice from all you experienced users would be very welcome.
Btw - I think I got around the Fade transition issue somewhat further by switching to the Merge transition which gives much better results - especially when the transition time is reduced from 500 ms down to 200 ms or even less. I noticed that all the other transitions (e.g. Wipe, Zoom, etc.) do not show any image degradation - its just the Fade transition that is the issue(?)
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 3/20/2014(UTC) Posts: 2,721 Location: Bordeaux, France Thanks: 243 times
Was thanked: 794 time(s) in 589 post(s)
|
Hi Pesi Good to know you could improve your quality. However if quality is really a concern to you, you should increase your bitrate. I know you can't, but you must understand that this is the number 1 factor for image quality. You will never get the best quality with such a low bitrate. Also, just to make sure, I'd suggest you try another platform as a comparison. I never used MetaCDN myself but some OVPs transcode the streams coming in and this can degrade the image quality. Even if my customers don't need fullHD, I always stream FullHD and work with an OVP that does the "multiscreen" transcoding (meaning transcoding my stream into all resolutions for all types of devices). And I always stream the best quality I can to the platform (i.e. 1080p at 8Mbits or more). This way I'm sure that the original feed is perfect. When it comes to transcoding, they have a perfect feed as a source. Then my customers can always get the best solution depending on their device and bandwidth. It makes a lot of difference. You can try YouTube for free and check this for example. Quote:is there any downside to using the High profile I gave you links to understand... You should have noticed that HIGH is for HD Quote: I reset the Level drastically to 1.1 from 3.1 – is this a factor? Can it cause problems for viewers/stream providers? Take time to study what it means... Doing anything won't lead you anywhere... Stick to 3.0 or 3.1 for MAIN SD Quote:Set the Preset to Very Slow – is this a problem? Which gives better quality – Very Slow or UltraFast? Already gave you this answer... "The faster, the worse" so VerySlow gives better encoding results at the expense of more CPU load Quote:What effect will changing the Threads have? Should one increase it from 4? The optimal value for this depends on your CPU and how many cores it has Quote:Also when adding a camera input (I am using SD NTSC cameras connecting through Firewire inputs into the laptop)…
1. Should the Input be set as DVI or Composite?
2. What should the Video Format be set as? The default is UYVY but should it be changed to something else like H264 (since that is what I am streaming as) or maybe something else like RGB24/32?
Any advice from all you experienced users would be very welcome.
Btw - I think I got around the Fade transition issue somewhat further by switching to the Merge transition which gives much better results - especially when the transition time is reduced from 500 ms down to 200 ms or even less. I noticed that all the other transitions (e.g. Wipe, Zoom, etc.) do not show any image degradation - its just the Fade transition that is the issue(?) If you can't see a difference for all this, stick to defaults settings. They were not chosen randomly. But again, increase your bitrate and you'll see a major difference. OR Try to stream to 1080p on Youtube, check the SD result and you'll see a major difference.
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 10/1/2016(UTC) Posts: 117 Thanks: 88 times
Was thanked: 52 time(s) in 31 post(s)
|
Pesi
Well I am a Wirecast user that is still in the process of switching over to vmix, our mac systems still run wirecast.
We often only have limited bandwidth in remote areas and have to stream sd at 400 to 600 kbps and one rule I always have my teams do at these lower bandwidths is to use cuts and try to stay away from all fades.
Like DWAM has mentioned this all comes down to your bitrate and unless you increase it you will get artifacts in your cross fades and graphic fades.
-s
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 1/29/2017(UTC) Posts: 140 Location: Squamish Thanks: 54 times
Was thanked: 4 time(s) in 3 post(s)
|
SHMD wrote:
We often only have limited bandwidth in remote areas and have to stream sd at 400 to 600 kbps and one rule I always have my teams do at these lower bandwidths is to use cuts and try to stay away from all fades.
Like DWAM has mentioned this all comes down to your bitrate and unless you increase it you will get artifacts in your cross fades and graphic fades.
-s
The confusing thing is - the same settings and low bitrate in Wirecast gave me perfectly smooth fades??? Why would it be different for the 2 softwares? Puzzling! Anyway, just like yourself I have switched my transitions over to cut instead of fade.
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 1/29/2017(UTC) Posts: 140 Location: Squamish Thanks: 54 times
Was thanked: 4 time(s) in 3 post(s)
|
DWAM wrote:Hi Pesi
Also, just to make sure, I'd suggest you try another platform as a comparison. I never used MetaCDN myself but some OVPs transcode the streams coming in and this can degrade the image quality.
Even if my customers don't need fullHD, I always stream FullHD and work with an OVP that does the "multiscreen" transcoding (meaning transcoding my stream into all resolutions for all types of devices). And I always stream the best quality I can to the platform (i.e. 1080p at 8Mbits or more).
This way I'm sure that the original feed is perfect. When it comes to transcoding, they have a perfect feed as a source. Then my customers can always get the best solution depending on their device and bandwidth. It makes a lot of difference. You can try YouTube for free and check this for example.
That is a great suggestion - I'll give it a try right away. What puzzled me though was that using the same OVP gave such different results for vMix and Wirecast (?) - kept all the settings strictly the same. Just the fade transition was slow and blocky - the remaining image quality was perfect and showed absolutely no degradation. Thanks for all the useful info.
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 10/1/2016(UTC) Posts: 117 Thanks: 88 times
Was thanked: 52 time(s) in 31 post(s)
|
pesi wrote:
The confusing thing is - the same settings and low bitrate in Wirecast gave me perfectly smooth fades??? Why would it be different for the 2 softwares? Puzzling!
Anyway, just like yourself I have switched my transitions over to cut instead of fade.
I never noticed smooth fades on two of our systems running Wirecast 7... the fade is pretty quick but still pixelated at low SD bitrates that is why we just use cuts on low bitrates. Now that is wirecast on Mac systems, so I can not comment on the PC version. But it does seem strange... -s
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 1/29/2017(UTC) Posts: 140 Location: Squamish Thanks: 54 times
Was thanked: 4 time(s) in 3 post(s)
|
Quote:Also, just to make sure, I'd suggest you try another platform as a comparison. I never used MetaCDN myself but some OVPs transcode the streams coming in and this can degrade the image quality. Tried it - no luck! Same result :-( I give up - from now on no fades, just cuts. Thanks to all of you guys for all your advice. Pesi
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 3/7/2012(UTC) Posts: 2,636 Location: Canada Thanks: 33 times
Was thanked: 506 time(s) in 475 post(s)
|
@ pesi
It does seem strange, have you tried reverting back to Wirecast again to ascertain that the issue is a software and/or encoding issue?
There has to be a technological explanation if the two softwares deliver different results on the same transition effect, namely a basic fade...
Ice
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 1/29/2017(UTC) Posts: 140 Location: Squamish Thanks: 54 times
Was thanked: 4 time(s) in 3 post(s)
|
I did try reverting back to Wirecast - with the same results. Smooth fade in WC and blocky fade in vMix.
It has to be something as yet undetermined in vMix (?)
Anyways - its only Cuts from now on! :-)
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 10/30/2013(UTC)
Posts: 290
Location: The Netherlands
Thanks: 6 times
Was thanked: 21 time(s) in 15 post(s)
|
DWAM wrote:VerySlow gives better encoding results at the expense of more CPU load
When I use my CPU for encoding then I can see a big difference in CPU usage between veryfast and medium. But when I am using my GTX 750 ti for hardware encoding is doesn;t matter which preset I choose, the GPU usage is the same and no visible differences. I am using the Nvidia GPU meter gadget, it shows 0% and after starting vMix app. 20%, but when I start streaming (hardware encoder enabled) the usage drops to 7%. Don't know why it drops, the CPU load is not getting higher, so the GTX 750 does the streaming job.
|
|
|
|
|
|
Rank: Advanced Member
Groups: Registered
Joined: 3/20/2014(UTC) Posts: 2,721 Location: Bordeaux, France Thanks: 243 times
Was thanked: 794 time(s) in 589 post(s)
|
Quote:When I use my CPU for encoding then I can see a big difference in CPU usage between veryfast and medium.
But when I am using my GTX 750 ti for hardware encoding is doesn;t matter which preset I choose, the GPU usage is the same and no visible differences.
You're right, this setting is useless for GPU encoding. Vmix encoder settings underlies FFMPEG on CPU, it does not show options for GPU encoding
|
|
|
|
|
|
Forum Jump
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.
Important Information:
The vMix Forums uses cookies. By continuing to browse this site, you are agreeing to our use of cookies.
More Details
Close
