Question / Help I Need Help Regarding Local Recording Settings

[BluesAdam]

Hi everyone,

First of all, my system is as follows:

AMD FX 6350 CPU @4.2ghz
MSI RX460 2gb GPU
2x4gb G Skill Ripjaws DDR3 1600mhz Ram
2x1TB Western Digital 7200rpm Caviar Blue HDD

I have a YouTube channel and I have been recording since two years but could never really grasp the system behind choosing the right settings and my videos tend to look really muddy, no matter what bitrate or CRF value I choose. To keep things simple, here are the settings I use in OBS Studio:

http://imgur.com/a/6WheJ

Basically, the only thing I changed was the QP values, both set to 20. I have good video quality, bearable video size (8 minutes video has 1.3gb of file size) in 1080p 30fps. However, I have noticed something really weird today. Because HitFilm 4 Express does not support h265 file support, I used ffmpeg to convert this 8 minute long video, from h265 .mkv into h264 .mp4 and something really surprising happened. I will try to explain as clearly as possible.

First of all, the command I used to convert the video was this:
ffmpeg -i inputfile -map 0 -c:a copy -c:s copy -c:v libx264 output.mp4

The h265 .mkv file has a bitrate of 23066 kbps and takes 1.3 gb of disk space. The converted h264 .mp4 file, however, has only 5778 kbps bitrate and takes 333mb of space. The thing is, no matter how close I look, I can not notice a difference in video quality, image quality is the same. This made me think that, if I can achieve the same video quality with only 5mbps bitrate, why is OBS recording it with 23mpbs bitrate. Can I actually use lower settings and still get the same video quality? So I came here to ask to settle this problem once and for all.

Are the settings I use overkill? I am basically using Constant Rate Factor of 20, which I don't think is very high. What can I do to find the optimal settings. I have spent hours on hours to find good settings but after this incident I am completely baffled and I think that I am doing something very wrong and wasting so much of the system resources for no reason.

I hope you can help me with this problem and thank you all for your answers in advance. Peace out.

 

[Fenrir]

Because live encoding is very different than transcoding after the fact when you don't have to do it in realtime.

 

[BluesAdam]

Because live encoding is very different than transcoding after the fact when you don't have to do it in realtime.

So, if I transcode the source file in Handbrake or using ffmpeg, could I indeed reduce the file size without losing much of the quality?

 

[Sapiens]

As long as the original recording looks good and your Handbrake settings aren't configured to significantly degrade the quality, sure.

 

[BluesAdam]

As long as the original recording looks good and your Handbrake settings aren't configured to significantly degrade the quality, sure.

Thank you so much, this well help me a lot.

 

[Xaymar]

There's also the thing that you're recording with Constant QP, which quite literally throws any potential compression mechanisms out the window as it always uses a fixed value for those. Great for when you want to record at high quality and then transcode using x264 or ffmpeg to something lower size but same quality (crf 15 for example).

 

[BluesAdam]

There's also the thing that you're recording with Constant QP, which quite literally throws any potential compression mechanisms out the window as it always uses a fixed value for those. Great for when you want to record at high quality and then transcode using x264 or ffmpeg to something lower size but same quality (crf 15 for example).

So, which method would you prefer? Variable bitrate or constant bitrate? Which would be a better choice. I have always been told that CQP or CRF was the best choice. I used to use around 15-20mbps variable bitrate but literally got yelled at as to why I wasn't using CRF or CQP. Everyone told me those were the better choices since they gave constant image quality.

 

[Xaymar]

I prefer Constant QP, large file size but also best quality - works great for my editing flow. CBR and VBR are only useful if you are really low on disk space or streaming.

 

[BluesAdam]

I prefer Constant QP, large file size but also best quality - works great for my editing flow. CBR and VBR are only useful if you are really low on disk space or streaming.

Thanks for the advice. Since I have a dedicated 1tb hard drive for video recordings, I will keep using CQP then. Appreciated.