Transcoding problems

Channels DVR Server Troubleshooting
#1

ffmpeg causes cpu on my dvr box to go to 100% when i use iphone to watch tv remotely - and the feed just lags every few seconds. Enabling HEVC transcoding in settings -> advanced -> experimental fixes the issue (low cpu + iphone feed is happy).

However when I enable the HEVC, a remote TV with a fireTV4k can't view the feed at all.

channels 2025.10.21.1818 on devuan/x64. transcoder set to hardware, debug info here

without hevc, ffmpeg is called like

dvr1$ ps -ef | Grep ffm
root     27388 26279  2 20:06 ?        00:00:00 /home/dvr1/channels-dvr/2025.10.21.1818/ffmpeg -hide_banner -nostats -loglevel warning -progress http://127.0.0.1:8089/hls/progress?key=ch29.1-dANY-ip192.168.1.1-remux -fflags discardcorrupt+genpts -f mpegts -probesize 8000000 -i - -enc_time_base -1 -max_muxing_queue_size 4096 -muxdelay 0 -map 0:v:0? -map 0:a? -ignore_unknown -map 0:s? -c:v copy -c:a copy -c:s copy -f hls -hls_time 1.000000 -hls_list_size 3600 -hls_delete_threshold 1 -hls_flags temp_file+delete_segments -start_number 1 -hls_passthrough_subtitles 1 /home/usb0/channels-data/Streaming/sessions/ch29.1-dANY-ip192.168.1.1-2883462901/remux/stream.m3u8
root     27394 26279 33 20:06 ?        00:00:06 /home/dvr1/channels-dvr/2025.10.21.1818/ffmpeg -hide_banner -nostats -loglevel warning -hwaccel vaapi -hwaccel_output_format vaapi -noautorotate -progress http://127.0.0.1:8089/hls/progress?key=ch29.1-dANY-ip192.168.1.1-1-h264-aac-copy--7488-256-720-6-0--hardware-false-false-0.01-0 -fflags discardcorrupt+genpts -f mpegts -copyts -probesize 8000000 -i - -enc_time_base -1 -max_muxing_queue_size 4096 -muxdelay 0 -map 0:v:0? -map 0:a? -ignore_unknown -map 0:s? -c:v h264_vaapi -g:v 60 -force_key_frames:v source -noautoscale -color_range tv -init_hw_device vaapi=intel:/dev/dri/renderD128 -filter_hw_device intel -bsf:v h264_mp4toannexb -profile:v 100 -filter:v format=nv12|vaapi,hwupload,deinterlace_vaapi=auto=1,scale_vaapi=-2:min(ih\,720):format=nv12 -b:v 7488k -minrate 6739k -maxrate 8236k -bufsize 14976k -c:a aac -ac 6 -b:a 256k -filter:a aresample=async=1 -c:s copy -f hls -hls_time 0.010000 -hls_list_size 360000 -hls_delete_threshold 1 -hls_flags temp_file+delete_segments -start_number 1 -hls_passthrough_subtitles 1 /home/usb0/channels-data/Streaming/sessions/ch29.1-dANY-ip192.168.1.1-2883462901/encoder-1-1467164479/stream.m3u8

Can I get a hand figuring out why cpu is going to 100% with iphone remotely and not hevc, or else can I enter a feature request to set transcoding method on a client-by-client basis (so i can pin the iphone to hevc)

#2

Please go to Support -> Troubleshooting -> Submit Diagnostic Logs from the web interface of the DVR and let us know when it's been submitted so we can have a better idea of what was going on.

#3

4e081f3e-b742-4d5a-9853-fa341134c4ec

#4

Which channel were you watching when you had this CPU issue when using H.264?

#5

29.1 and 129.1

#6

Is your computer really running an Intel Haswell chip?

#7

yep. its an elitedesk 800 G1 with i5-4590T

#8

I'm sure Eric will have a proper answer for you, but using a 12 to 13 year old CPU will limit what can be encoded and decoded with the iGPU and fall back to software transcoding which might be what is causing the 100% CPU usage.

1 Like
#9

The 129.1 ATSC3 channel is already HEVC so it could be why it’s able to send that without actually transcoding when you enable HEVC.

Please try the non-ATSC3 29.1 channel and then submit diagnostics again if it still exhibits the issue.

1 Like
#10

Separately, if you could upload “NFL Football Chicago Bears at Baltimor 2025-10-26-1259.mpg” to us that would be helpful in tracking down another issue:

https://www.dropbox.com/request/MMjICRc053JJpSBPDIfQ

#11

done

#12

actually 129.1 wont play on the iphone at all when remote (i didnt realize there was a behavior difference until i paid closer attention).

there's just a constant spinny circle on the channels app when trying to watch remote -- without hevc ffmpeg stays at 100% and with hevc, channels-dvr is ~13% and ffmpeg at ~2%.-- but always just spinny circle and no video/audio.

172ac095-4486-4472-a73a-17a99c2b9b73

for 29.1, i changed the Deinterlacer to Hardware which calms down ffmpeg to 35% cpu and the iphone can watch the feed without hevc.

c283185a-64c3-4f2b-868b-90771992ada3