CPU vs Nvidia GPU for pre-encoding movies to stream

[wakeboarder141 40]

I am pre-encoding (correct term?) movies with Handbrake for streaming from my NAS to prevent the NAS having to transcode on the fly.  With my current internet speeds, I am encoding them at about 8mbps.  I played around a little with using the GPU instead of CPU to do the encoding, and the speed difference is incredible.  Is there going to be a large quality difference if I switch to using the GPU?  I am looking at a list of about 500 more movies and wondering if saving a couple hours of encoding per movie might be worthwhile, but if it ends up being a poor finished product I will just keep it as-is.  I am using a Intel 9900K and a Geforce 2080ti on Windows 10.

Edited December 9, 2020 by wakeboarder141

[Happy2Play 9783]

In the end it will be up to you.  I would just do a couple and compare.  But each method will used different default settings.

[wakeboarder141 40]

1 minute ago, Happy2Play said:

In the end it will be up to you.  I would just do a couple and compare.  But each method will used different default settings.

Thanks for the input.  I was thinking there would be some people with a lot of experience in this that might already have a definitive answer on what is going to change between the two.

[Ronstang 294]

1 hour ago, wakeboarder141 said:

Is there going to be a large quality difference if I switch to using the GPU?

From my experience no.  Now I will qualify that by saying it is really hard to tell on something as subjective as this and I am rather picky about quality and when I made the switch to using my nVidia GPU I did some rather extensive testing encoding all different types of movies using both the CPU only and then using the GPU assist and and when I was done I started doing all my movies with hardware acceleration (GPU) because they take about a quarter of the time.  I have done thousands of movies this way since June and I watch them using my Firestick 4K and the quality is incredible to me.....and most of my movies are recorded from TV.  Blu-Ray discs encoded look amazing and DVDs look surprisingly really nice too.

I don't think you will be sorry switching to encoding and storing your movies.  I have been doing it for a year and I have 4500 movies and could not be happier with the convenience and the quality. 

[wakeboarder141 40]

1 hour ago, Ronstang said:

I don't think you will be sorry switching to encoding and storing your movies.  I have been doing it for a year and I have 4500 movies and could not be happier with the convenience and the quality. 

Thanks for the suggestions.  I guess I need to figure out how to set it up to keep the bitrate under my limit like I do with the cpu encodes and see how it looks.  I'm not sure if the same advanced options I have set up now will transfer over to the GPU encode or not.

[Carlo 4561]

I think it depends on the generation of GPU you have.  I recently upgraded to an Nvidia GTX 1650 and have two encoding jobs going constantly converting my remaining library to h.265.

I do notice a bit of size difference compared to CPU only but quality has been fine.  For me it's well worth the tradeoff.

[Ronstang 294]

Same for me as Cayars, we both switched to GTX 1650s the same week and although I can run 4 encode jobs simultaneously I only run 2 to leave other resources free on the machine and the file size is just a little bigger with GPU over CPU encoding but the quality is pretty much the same at similar bitrates. In my opinion using a little more space is acceptable that I use an eighth the time to encode.

[wakeboarder141 40]

1 hour ago, Ronstang said:

Same for me as Cayars, we both switched to GTX 1650s the same week and although I can run 4 encode jobs simultaneously I only run 2 to leave other resources free on the machine and the file size is just a little bigger with GPU over CPU encoding but the quality is pretty much the same at similar bitrates. In my opinion using a little more space is acceptable that I use an eighth the time to encode.

How are you doing the multiple encodes at once?  Multiple instances of Handbrake running?  What kind of bitrate are you targeting that has the acceptable quality you are seeing? I am running a gtx 2080ti

Edited December 12, 2020 by wakeboarder141

[Carlo 4561]

I use ffmpeg personally.  For batch conversions which I have going on against my library at present I use ffmpeg Batch AV Converter with a custom command line.
https://sourceforge.net/projects/ffmpeg-batch/

[Ronstang 294]

On 12/12/2020 at 11:30 AM, wakeboarder141 said:

How are you doing the multiple encodes at once?  Multiple instances of Handbrake running?  What kind of bitrate are you targeting that has the acceptable quality you are seeing? I am running a gtx 2080ti

Sorry, I have been out of town.  Once again I agree with Cayars, I prefer ffmpeg....mostly because it uses less resources on my machine....and at his suggestion I have played with ffmpeg Batch AV Converter but my main software for conversions is MCEBuddy.  I record a lot of movies commercial free from Cable and although I don't use the commercial skipping feature, even when there are commercials,  I like MCEBuddy for all it's features.  I mainly use it because I like the ability to extract the subtitles from the recorded movies, convert them to SRT, and re-insert them into the MKV container and queue up 200 conversions and leave town.  MCEbuddy will also use as many simultaneous conversions as supported by your GPU.  I have run it with 4 conversions at a time but my computer was pretty much unusable and I rely on it to record my movies.

With MCEBuddy you can use ffmpeg or Handbrake, it comes with both configured but Handbrake is the default priority which would work good for you if you like Hanbrake.  I simply edited my profiles to use ffmpeg first so it never even uses Handbrake.  You can also edit the profiles to customize them to your liking.  I am still trying to figure out what are the best settings to use for HEVC (H.265) to achieve the quality I want.  The default in MCEBuddy are fine for most movies and result in considerably smaller files than H.264 but in dark movies or dark scenes it can result in a haloing affect that looks bad to me.  I will continue to test after the Holidays and if your are interested I will post my new HEVC Hardware Accelerated profile once I make a decison.

[Carlo 4561]

I like MCEBuddy and use it to cut commercial.  But I manually edit them as well to fix the beginning, ending and any missing cuts it made.  So I have MCEBuddy set to NOT do any conversions but only cuts.  I do a lot of recording of cable channels which are already H.264 on xfinity/comcast so I don't want MCEBuddy doing a conversion from H.264 to H.264.  So I have MCEBuddy place these "first pass" edits in a directory I then edit by hand.

I can edit full length movies on average of 1 to 2 minutes so I don't mind doing this for better quality.  I use AVIdemux as the editor.  I then save this data to another staging directory.

This staging directory get's processed by another automated script called sickbeard_mp4_automator which I have setup to COPY video, create a 2 track normalized audio track as well as remove non English subs and audio track (unless it's not properly marked or undefined).  The script then creates an SRT sub file from the Closed Caption that was in the file.

At this point the file gets staged again where it is processed for video where I create a new file with H.265 copying the audio, subs over with it.  Once the file is converted I compare this new file size to the pre-converted file.  If the file is not at least 90% of the original pre-stage file I'll keep the "original" and delete the h.265 version as I didn't save enough space (or could have been bigger) to warrant using the h.265 version. Most of the time the converted file will get much smaller (30% to 70%) so it will get used and the pre-stage version is deleted.

It now runs through Filebot which will rename if needed, create the proper folder and place the files in it for Emby to scan.

Sounds complex but really isn't and besides the manual edits I do for recorded TV is fully automated. 

I do have the stage directories as part of my Recording library setup so they are available (regardless of stage).  This allows me to do edits once or twice a week when I have spare time.