Hardware transcoding

Josu Lazkano

Hello,

I have a Tvheadened server that feed 4 Libreelec frontends, it really works great. But I want to compress the video stream to some remote users.

Which is the best hardware to trancode the streams?

My CPU is "Intel(R) Core(TM)2 Duo CPU E8200 @ 2.66GHz", so I can not transcore it.

I will appreciate your help.

Best regards.

Robert Cameron

The best would be the h264_vaapi that is now in ffmpeg. However, currently the vaapi hardware encoding support in Tvheadend is not working. Your hardware is sufficient, though. On a less powered Intel system, I am able to get ~5% CPU usage while transcoding 1080P MPEG2 into H264 using ffmpeg's h264_vaapi.

Josu Lazkano

Thanks Robert,

Please, could you show how to configure it?

I never use transcoding profiles in Tvheadend.

About vaapi. Isn't it related to GPU? My server has not any GPU card. It could be enough adding a specific card? It will be great for me.

Thanks for your help and best regards.

Robert Cameron

VAAPI is Intel's open/general hardware en-/decoding API that uses its HD Graphics system, which is the integrated GPU in Intel processors.

QSV (Quick Sync Video) is Intel's closed/proprietray hardware en-/decoding API; QSV requires additional kernel modules and specific SDKs from Intel, whereas VAAPI does not.

ffmpeg has supported QSV for quite some time, but getting it configured properly is no easy feat; starting in 3.0, ffmpeg also includes VAAPI support, which is much easier to use.

Unfortunately, the VAAPI encoders as compiled into Tvheadend are broken, so I can't really give any tutorials. You can use an IPTV pipe:// input and use ffmpeg to do your transcoding, but it's not particularly easy to set up, either. (It rarely works for me ... but it's not a huge issue for me because I don't use transcoding.)

Josu Lazkano

Thanks again Robert,

So I need to use ffmpeg trancoding pipe.

Anyone could help with a example? I use HD content in most of the channels.

Kind regards.

Josu Lazkano

I try "webtv-h264-aac-mpegts" in "Streaming profiles" and the server goues 100% CPU load.

I will appreciate your help.

Regards.

Robert Cameron

To use VAAPI with ffmpeg, check if your build of ffmpeg has vaapi support built in with :

ffmpeg -codecs | grep vaapi@. Then, when you construct the command line for ffmpeg: @ffmpeg -hwaccel vaapi -hwaccel_device /dev/dri/render/D128 -hwaccel_output_format vaapi -i - -vf 'format=nv12|vaapi,hwupload' -c:v h264_vaapi -c:a copy pipe:1

That will take input from the standard input (such as for use with pipe://), use VAAPI to encode the video the H.264, but copy the audio stream as-is without re- or transcoding, and pass it back out to the standard input.

If you also need to resize the video, use the

scale_vaapi

video filter; just add it as an additional filter to the

-vf

option. So from the previous example, the video filter becomes:

-vf 'format=nv12|vaapi,hwupload,scale_vaapi=w:h'

where

and

h

are the width and height of your new video.

Hope this helps as a starting point.

As a note, you might need to ensure that the user running the command is a member of the video group, or which group has write access to /dev/dri in order to use VAAPI.

Josu Lazkano

Thanks again Robert,

I have no GPU card in the server, but I have this DRI devices:

# ls -l /dev/dri/ total 0 crw-rw---- 1 root video 226, 0 sep 18 00:11 card0 crw-rw---- 1 root video 226, 64 sep 18 00:11 controlD64

# lspci | grep VGA 00:02.0 VGA compatible controller: Intel Corporation 82G33/G31 Express Integrated Graphics Controller (rev 02)

I try to add a Stream Profile, but which option must I select here?

http://i67.tinypic.com/27zddsk.png

I really appreciate your help.

Kind regards.

Robert Cameron

Looks like you may not the necessary drivers, or your hardware may not support VAAPI.

As far as the streaming profile, if you add

-f mpegts

before the

pipe:1

in the ffmpeg command line, it will create a MPEG-TS, and then just use the pass-through profile.

(Of course, this is for ffmpeg being used with the IPTV Network input, and a mux defined as a pipe:// resource.)

To see if your setup has the proper drivers and hardware, check what the output of

vainfo

is.

Josu Lazkano

Thanks again.

I will try to add a ATI GPU in ther server and test it.

Which GPU card could be good for that? It just wotk with ATI? Or could I use Nvidia?

Best regards.

Christian Brauwers

Have an Eye on this Board : https://www.supermicro.com/products/motherboard/Xeon/C236_C232/X11SSV-M4.cfm

The Intel Iris P580 GPU can transcode up to 15 HD Channel at time !

Josu Lazkano

Thanks Christian,

It cost 1000$. Too much for me.

It looks great, but 15 HD transcoding is too much, I have enough with 2-3 HD transcoding.

Is it possible adding a GPU card to actual server?

Regards.

Robert Cameron

Of course it is possible to add a GPU to a server and use it for transcoding. It all depends upon the drivers and tools you want to use, and what types of hardware acceleration they support.

Josu Lazkano

Thanks,

I want to know your experience about GPU cards. I need just trancode 2 HD streams.

Regards.

Christian Brauwers

couldn't you try Rpi 2/3 for transcoding? with new ffmpeg 3.1 HW encoding is supported ... cost round about 35 eur per Rpi

Jonathan Thomson

It still needs the TVHeadend developers to build support for it though :(

I think there's a way to use pipe to transcode but it sounds messy to me.

Christian Brauwers

why? you can build simple php script or something else to map this ...
i will get some new rpi3 these days so i have 2 rpi2 for testing ... will try with ffmpeg 3.1 on rpi2 ...

Peter Tofte

Hi Robert

I have the ffmpeg command working with vaapi.

/usr/bin/ffmpeg -re -y -vaapi_device /dev/dri/card0 -hwaccel vaapi -hwaccel_output_format vaapi -i /home/hts/in.mkv -an -vf 'format=vaapi|nv12,hwupload' -c:v h264_vaapi -qp 20 -f mpegts -tune zerolatency -f mpegts out.ts

When I try to create a pipe in tvheadend (in the url text box) i put

I get the following error message:

2017-01-21 09:48:31.621 spawn:     Stream #0:0(eng): Video: h264 (High), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 29.97 fps, 29.97 tbr, 1k tbn, 59.94 tbc (default)
2017-01-21 09:48:31.621 spawn: [AVFilterGraph

0x5635f9d5ae00] No such filter: 'format=nv12|vaapi,hwupload'
2017-01-21 09:48:31.621 spawn: Error opening filters!

2017-01-21 09:48:31.623 iptv: stdin pipe unexpectedly closed: No data@

I was able to make a pipe working with avconv and an online rstp stream, but not with vaapi. So pipe is fundamentally working in tvheadend. Question is, why is it not working with my vaapi command.

I also tried to create a #bin/bash script and calling this script from the pipe url in tvheadend, but no luck.

I am opening the iptv mux with vlc.

Any ideas? Did you get it to work?

-Peter

Robert Cameron wrote:
> To use VAAPI with ffmpeg, check if your build of ffmpeg has vaapi support built in with :

ffmpeg -codecs | grep vaapi@.
> 
> Then, when you construct the command line for ffmpeg:
> 
> @ffmpeg -hwaccel vaapi -hwaccel_device /dev/dri/render/D128 -hwaccel_output_format vaapi -i - -vf 'format=nv12|vaapi,hwupload' -c:v h264_vaapi -c:a copy pipe:1

>
> That will take input from the standard input (such as for use with pipe://), use VAAPI to encode the video the H.264, but copy the audio stream as-is without re- or transcoding, and pass it back out to the standard input.
>
> If you also need to resize the video, use the

scale_vaapi

video filter; just add it as an additional filter to the

-vf

option. So from the previous example, the video filter becomes:

-vf 'format=nv12|vaapi,hwupload,scale_vaapi=w:h'

where

and

are the width and height of your new video.
>
> Hope this helps as a starting point.
>

> As a note, you might need to ensure that the user running the command is a member of the video group, or which group has write access to /dev/dri in order to use VAAPI.

Robert Cameron

Peter Tofte wrote:
> Hi Robert
>
> I have the ffmpeg command working with vaapi.
>
>

/usr/bin/ffmpeg -re -y -vaapi_device /dev/dri/card0 -hwaccel vaapi -hwaccel_output_format vaapi -i /home/hts/in.mkv -an -vf 'format=vaapi|nv12,hwupload' -c:v h264_vaapi -qp 20 -f mpegts -tune zerolatency -f mpegts out.ts

>
> When I try to create a pipe in tvheadend (in the url text box) i put
>
>

/usr/bin/ffmpeg -re -y -vaapi_device /dev/dri/card0 -hwaccel vaapi -hwaccel_output_format vaapi -i /home/hts/in.mkv -an -vf 'format=vaapi|nv12,hwupload' -c:v h264_vaapi -qp 20 -f mpegts -tune zerolatency -f mpegts pipe:1

>
> I get the following error message:
>

2017-01-21 09:48:31.621 spawn:     Stream #0:0(eng): Video: h264 (High), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 29.97 fps, 29.97 tbr, 1k tbn, 59.94 tbc (default)
> 2017-01-21 09:48:31.621 spawn: [AVFilterGraph

0x5635f9d5ae00] No such filter: 'format=nv12|vaapi,hwupload'
> 2017-01-21 09:48:31.621 spawn: Error opening filters!
> 2017-01-21 09:48:31.623 iptv: stdin pipe unexpectedly closed: No data@
>
> I was able to make a pipe working with avconv and an online rstp stream, but not with vaapi. So pipe is fundamentally working in tvheadend. Question is, why is it not working with my vaapi command.
>
> I also tried to create a #bin/bash script and calling this script from the pipe url in tvheadend, but no luck.
>
> I am opening the iptv mux with vlc.
>

> Any ideas? Did you get it to work?

You have a couple of problems with your options for

ffmpeg@.

* @-re

– This option is used to slow the reading of on-disk files to real–time for live streaming output. When used with live stream inputs, it can cause problems when

ffmpeg

attempts to re-adjust the framerates. Donot use this option live/real–time inputs. (Looking at your example, it is hard to tell if you are using the

/home/hts/in.mkv

as a test input, or if you are really using a file for your IPTV mux. If you are really using an on-disk file, then keep the

-re

option.)
*



-vaapi_device /dev/dri/card0

– VA-API hardware encoding does not use the

/dev/dri/card*

device, but rather

/dev/dri/render*@. On my systems the device is @/dev/dri/renderD128@, but it may be different on yours.
* @-tune zerolatency

– The

-tune

options are for using

libx264

as your encoder, and have no effect when using

h264_vaapi

as your encoder.
*



-qp 20

– This is basically unnecessary, as the default

-qp

setting for

h264_vaapi

is already 20. The scale is the same as the

-qp

and

-crf

options for

libx264@: 0-51, with lower numbers having higher quality; sane values should remain between 18–28 if you are going to use this setting. So, you may want to try this as your URL for the IPTV mux: @pipe:///usr/bin/ffmpeg -hwaccel vaapi -vaapi_device /dev/dri/renderD128 -re -i /home/hts/in.mkv -vf format=nv12|vaapi,hwupload -an -c:v h264_vaapi -f mpegts -flags +global_header pipe:1

I have had problems with quotes in

pipe://

URLs, so I tend to leave them out as they only seem to make things more difficult, regardless of how I escape them, and regardless of whether they are

"@. Also, I have had problems with MPEG-TS headers needing to be present for Tvheadend, so I have added the @-flags +global_header

option to ensure those are generated and added into the MPEG-TS.

Peter Tofte

Hi Robert,

that did the trick. I didn't notice the card0 issue, I know it has to be renderD128. The " ' "s are causing problems..I think its better to place the actual ffmpeg command in a shell script. I will ditch the "-re" option, it doesn't make sense for live tv anyway, as the in-pipe will only provide data real-time anyway - right?

I am now able to transcode live tv (yes the in.mkv was merely a test setup) using vaapi. Only thing missing now is a way to cast to chromecast. Unfortunately chromecast only supports webm (transcoding required, and i dont have hardware supporting VP8 encoding) or MP4 which is no good for live TV due to some MOOV thing in the file header.

-Peter