Bug? Don't Transcode when source Bitrate is lower than requested Bitrate!

Channels DVR Server
#1

So I have a remote client that I want to reduce the max Bitrate to 4Mbps. I pay for data overage at that location so want to keep consumption lower if possible. Changed the setting in Client settings to 4Mbps to just effect that 1 device. I thought I was good..... nope!

This works great when watching my HDHR tuner ATSC1 channels. Bitrate is reduced from about 12Mbps to 4Mbps. Great!

BUT.... problem is, say I watch a movie that has a bitrate of 2Mbps, it takes that movie and Transcodes it UP to 4Mbps... YIKES! Now not only am I getting hit double the bandwidth, but I also am getting a degraded picture quality taking the original to a Transcode, but also the Server CPU is taking a 5% hit when not needed.

Is this "normal" behavior? If so, can I formally ask to have Channels change this policy to Direct Play media when the Source bitrate is Lower than the setting Bitrate? This was a problem with Emby back in the day but I reported this to Luke and he got it corrected!

#2

What is the codec of the 2mbps movie?

#3

Most of what I have h265

#4

Remote streaming uses h.264, which has lower quality-per-bitrate than h.265. We cannot mix codecs (h.264 and h.265) in the same stream with our Adaptive Bitrate code, so we must transcode other codecs to h.264. If we were to re-encode your 2mbit h.265 at 2mbit h.264 it would result in a drop in quality so we don't do that.

#5

Maybe I am not explaining it correctly but I don't want the files touched, just direct play/remux them exactly as they are if the source is say 2Mb and the remote client is set to 6Mb. That make sense?

#6

That is not how the streaming system works. If you set anything other than Original, you are using our Adaptive Bitrate infrastructure that will be able to handle decreases in network quality without the user having to touch any settings. To make this happen, we must transcode non-h.264 content to h.264, regardless of the bitrate. This is a design decision we have made for usability that we are not going to change.

If you would like to get the original source material, set the Streaming Quality to Original.

#7

Ok well another example is Ch 115.1 (local ATSC3 station) has a bitrate of about 1.50Mb. With the transcoding set to 8Mb it is taking that 1.50 stream and sending it as an 8Mb stream. Ch 3.2 has a bitrate of about 4Mb. It's taking that 4Mb stream and sending it at 8Mb.

I hate bitching and whining when you have an excellent product, but do you see the issue here? I don't think the way it is at the moment makes the most sense for users.

#8

8Mbps in mpeg2 is not the same as 8Mbps h264 is not the same as 8Mbps hevc. And the amount of bandwidth used is not constant.

If you're using h265 files and h265 atsc3, then you can stream in original or you can use the experimental h265 encoder option (with compatible hardware).

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#9

This could be solved by creating a custom m3u source for all the remote channels.

Combining URLs from

http://DVR_IP:8089/devices/ANY/channels.m3u?codec=copy

for channels w/o transcoding and

http://DVR_IP:8089/devices/ANY/channels.m3u?bitrate=3100

for channels with transcoding.

This would probably require hiding the HDHR sources on the client and making sure the "new" channels are not used for recording on the DVR. Setting a second DVR in the remote location and putting the M3U source there would probably help to make it cleaner.

#10

I agree if the bit rate is lower then it should be left alone or at least give users the option. I have run into this many times and just can't figure out why it would transcode when not needed.

1 Like
#11

You couldn’t figure out before this thread or you still can’t?

#12

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