Jump to content

transcode quality is quite different between Android and Web Clients


lolento

Recommended Posts

lolento

So I am testing the transcode quality on the Android client versus the Web Client.

 

It looks like the quality is quite different.  At 720kbps, the picture is smooth and acceptable (DVD quality) on the web client.  However, at the same bitrate, it is very pixelated on the Android client.

 

Is there a difference in terms of how the Android client initiates a transcode stream versus the web client?

Link to comment
Share on other sites

Redshirt

Can you run the same tests again, using the same movie for both and provide the server log so I can see what both clients are requesting.

Link to comment
Share on other sites

Redshirt

It looks like their may actually be a bug in the web client here.

 

Here's the playback requests the server received.

 

Android Client:

http://chilman408.blah.blah:8096/mediabrowser/Videos/640f7050114f3f3dc9336ea6b56e8278/stream.m3u8?MaxWidth=1920&audioCodec=Aac&level=3&VideoBitRate=522000&VideoCodec=H264&MaxHeight=1080&audiochannels=2&AudioBitRate=128000&TimeStampOffsetMs=0&profile=baseline&DeviceId=2e77e42e6fac74b3

If you add the video bitrate and the audio bitrate you have 650,000 which I'm rounding to 650kb/s even though it's not exactly.

 

Web Client:

http://chilman408.blah.blah:8096/mediabrowser/Videos/640f7050114f3f3dc9336ea6b56e8278/stream.m3u8?audioChannels=2&StartTimeTicks=0&SubtitleStreamIndex=&AudioStreamIndex=1&deviceId=6407a9d1ae9b13c4c3659fe6af08bf791e9dc523&Static=false&profile=baseline&level=3&timeStampOffsetMs=0&maxWidth=1280&videoBitrate=1372000&audioBitrate=128000&VideoCodec=h264&AudioCodec=aac

The same math is 1,500,000 which can be rounded to 1.5 mb/s. Or 2.5 times the bitrate of the Android client.

 

If you set the Android client to 1.5 mb/s the picture quality should be on par as the url requests will be similar.

Edited by Redshirt
Link to comment
Share on other sites

Redshirt

I deleted your post to hide your dyndns server address in the attached logs. 

Link to comment
Share on other sites

judging from the maxwidth coming from the web client, it looks like the 720p 1.5Mbps option was the selected quality. So the params look right but the comparison between the two apps is apples to oranges because 1.5Mbps will obviously look better then 720k.

 

There is a 720k 480p option in the web client but that couldn't have been selected based on the 1280 param.

Link to comment
Share on other sites

lolento

There is a 720kbps option on the web client but i cannot access it on the mobile browser. I tried thar bitrate this afternoon though and it look much smoother than the 650kbps from the android client... Let me try this again.

Link to comment
Share on other sites

lolento

Hello,

 

 

Attached new log files.  Play at web client at 720kbps and from android client at 850kbps.  The andriod transcode is still very pixelated, especially apparent when scene changes.

 

 

EDIT:  Deleted the attachment.

Edited by lolento
Link to comment
Share on other sites

Redshirt

Discussed those logs with our streaming expert Tikuf. Out of curiosity, are you watching the web client full screen? The resolution your asking from the web client is 720x405 @ 572 kb/s The resolution the Android client is asking for is 1280x720 @ 722 kb/s. The Android should be a higher quality image if you were to resize the web client window to the same dimensions.

Link to comment
Share on other sites

lolento

No, from the web client, I am using the pop up window which is still quite big.  But the quality difference is very apparent.

 

I think the lower bitrate going to a higher resolution maybe the issue; for the web client it is streaming 291600 pixels over 572 kb/s where as on the android client it is streaming 921600 pixels over 722 kb/s.  I don't know if this is the correct way of looking at it.

 

The transcode stream on the android client is very pixelated, a lot of macro blocking.  I would describe as looking at an 8-bit type image especially when there is a scene change.

Link to comment
Share on other sites

Redshirt

That's a very valid way of looking at it. You've very nearly answered your own question too. I was wrong with my above example.. ah well.

 

In the web client your asking for 291600 pixels per frame. In the Android client your asking for (well I'm asking for :) ) 921600 pixels per frame. That means the resolution is something in the neighbourhood of 3.17 times larger. So the bitrate of the Android client would need to be 3.17 times larger than the web client to equal the same quality. Or 1.8mb/s. Does that make sense?

Edited by Redshirt
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...