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Video bitrate


thisguy2626
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thisguy2626

The server is running on INTEL i5-3570k 3.40 gHz 16 GB ram windows 7 Home Premium x64

 

OK I'm hoping someone can help clarify this for me. Ive been reading on the server that if you have a file encoded with h.264 and aac in either mp4 or mkv containers then it will direct play to your device, so I have been experimenting a bit, and have yet to see no transcoding going on on my server with files that fit that description. But, while I was playing around with it, I noticed that if I increase my iphone 5's bitrate settings to higher than the bitrate of my video file, then the video will be jittery or freeze all together and the audio will sound off. I know next to nothing about this, but I had assumed that it should play better if the bit rate settings exceed the files settings?

 

For example, the file I am attempting to play is 5,368 kb/s. H.264 AC-3 in MKV container. 

VIDEO stream 4,877 kb/s 1920*1080 at 23.976 fp/s; AUDIO stream 384 kb/s 48 khz, 16 bit 6 channels AC-3.

 

I set the cellular quality bit rate settings in the MB ios app to 5 mb/s and it plays wonderfully over LTE. The audio is crisp, the video is clear and smooth during playback, but CPU utilization on my PC is very high, around 80-90%.

 

If I increase the bit rate on the iOS device to 6 mb/s, it takes longer to begin playback, and when it does the audio is hollow and the video freezes while the audio plays on, though on my PC the CPU utilization is significantly lower between 20-30%.

 

It happens with all of the files I have played with while on the cellular network and my LAN wifi, this is just the one I have open in mediainfo currently.

 

Why is the playback not improved by having the devices bit rate settings exceed that of the file?  Why is the CPU utilization so much higher when the bit rate levels are lower than the bit rate of the video file? Will I have to adjust the bit rate for each video file I watch? What settings will give me optimum playback quality for all video files remotely, over network and over wifi?

Also, if someone wants to try and explain the direct play concept to me that would be wonderful. I cannot seem to find a file that will play directly even though many of my video files fit the h.264 aac encode description, maybe it is because I am using an iOS device...

 

Thanks for any help you can give. This is confusing me and I would appreciate the insight.

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maybe it is because I am using an iOS device...

H.264 video up to 1080p or 720p for iPad mini or earlier version of iPad, 30 frames per second, Main Profile level 3.1 with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio;

 

MPEG-4 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio.

 

80-90% is transcoded both video and audio

20-30% was to copy video and transcoded audio

 

It is the audio codec causing you problems on ios7.

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darwindeeds

I will explain the Cellular bitrate issue first, When you are using a server url that is not within your local ip range then stream quality is capped by your ISP maximum upload speed. The upload cap can be pretty low based on your internet connection. So there are 2 aspects for smooth streaming, the server serving up the right quality content and the network being able to support the upload bandwidth. With that said, if you set your video/audio bitrate above your upload bandwidth, you will start seeing issues with streaming. So your 5mb/s is probably your upload cap. Even if you are in remote via that is well above the bit rate, it wouldn't matter.

 

As far as the local streaming goes, there are a lot of changes that has happened in the server that iOS client has not caught up with. We have an iPad app that is pending apple's review which has been build ground up for streaming with help from the server guys. I would try our test cases there and report to see if the issue happens. Eventually, the iPad app will become universal and the current iOS will be sunset'd. 

 

I hope this helps you to gain some perspective. 

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thisguy2626

Thanks for your reply. My upload cap is 11 mb/s.

 

Considering that and your reply, I would assume that the issue is with the application itself? In perfect, ideal circumstances, setting the bitrate to it's highest option in the application should yield the best results in terms of quality right? I'll play with it some more but I have a feeling that no matter what my upload speed and the videos bitrate is it will always happen if I set it higher.

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