<p>Decreasing the size a little won't help much, decreasing it a bit more induces a fair bit of aliasing (unless it smooths it also) butchering the quality without much gained.</p>

<p>Cutting the size 50% will reduce errors and double the jaggyness and be easily enough to save a lot of space, question is: Do you want 360P Video? You really wouldn't want any smaller.</p>

<p>So while that is one way to save space for Archiving I would recommend using 'Q' at 40 to test one file at 720P (output) and see if you can tolerate the quality.</p>

<p>H.265 has superior output quality as well as an approx. 50% reduction. Decreasing the resolution in half means an approx. 25% reduction alone, along with approx. 50% from H.265 your going to be under 15% WITH the same quality.</p>

<p>So decreasing the resolution from 720P will be either too drastic or induce greater errors in the output (it will begin to look like mush). Best to try using 'Q' alone as see where between 30 and 40 you can stand.</p>

<p>Here's an example from one particular Video YMMV.</p>

<p><img src="https://i.sstatic.net/JbtCt.png" alt="Compare H.264 vs. H.265 File Size"></p>

<p>Note that going from 24 to 40 gets you down to 10% (in that one example).</p>

CC BY-SA 4.0
2017-03-25T17:11:02.853Z
2019-01-20T21:36:06.127Z
2019-01-20T21:36:06.127Z
Rob
<p>In addition to suggestions above, you could also do a pulldown from 30fps to 24 fps. </p>

<p>This would likely not be noticeable to the average viewer; as 24p is the standard for film and narrative tv production. </p>

<p>You thus decrease the amount of discrete frames by a factor of 1/5 (20%). </p>

CC BY-SA 3.0
2017-03-26T05:31:57.743Z
2017-03-26T05:31:57.743Z
McFlySoHigh
<p>I think just turning it in H265 will reduce it of the 10% you need. To do it well you can bring it bac to uncompeessed yuv format using ffmep then encode the yuv in HEVC using HM référence software. </p>

CC BY-SA 3.0
2016-07-15T11:35:32.777Z
Why use the reference encoder? It's not well-tuned.
Gyan
CC BY-SA 3.0
2016-07-15T15:19:10.713Z
To be clear I mean I want the file to be 10% to 20% of the original size, hence a reduction of 90% to 80%. I think HEVC is only going to cut my file size in half at best?
BeeOnRope
CC BY-SA 3.0
2016-07-15T10:26:19.530Z
2016-07-15T10:26:19.530Z
frerechanel
<p>I have some 720p 30FPS H.264 video that I want to downsample for online backup. I want to get to somewhere around 10% to 20% of the existing size, which will evidently require a large sacrifice in quality. I will use H.265 as the destination format.</p>

<p>Now I have two main knobs I can turn to achieve this: I can lower the resolution, or I can lower the quality factor for the encoder. Of course, I can also combine both approaches.</p>

<p>How should I approach this to preserve as much quality as possible? It's pretty clear that turning the quality way down while keeping the resolution at 720 results in some pretty terrible video, but I'm not sure that I should draw the conclusion that I should mostly use resolution decreases to achieve the size reduction.</p>

CC BY-SA 3.0
2016-07-14T05:15:12.993Z
The choices will partly depend on how compressed the source is to begin with. Paste the [Mediainfo](http://mediaarea.net) readout for one of your source files. Use View -> Text mode.
Gyan
CC BY-SA 3.0
2016-07-14T20:05:30.830Z
And what about reducing the rate down to 15 fps?
RawBean
CC BY-SA 3.0
2016-08-06T13:36:41.577Z
Do you have audio as well?
Apeiron_Sound
CC BY-SA 3.0
2016-08-06T13:37:58.073Z
@Necrodeathify - yes there is a mono audio stream as well.
BeeOnRope
CC BY-SA 4.0
2019-01-22T02:54:11.640Z
10% of the original quality is not a backup, it is more like a proxy.
Rusty Core
<encoding><compression>
Trading off resolution vs quality
BeeOnRope
# Trading off resolution vs quality

(Asked by: username_0 on 2016-07-13)

I have some 720p 30FPS H.264 video that I want to downsample for online backup. I want to get to somewhere around 10% to 20% of the existing size, which will evidently require a large sacrifice in quality. I will use H.265 as the destination format.

Now I have two main knobs I can turn to achieve this: I can lower the resolution, or I can lower the quality factor for the encoder. Of course, I can also combine both approaches.

How should I approach this to preserve as much quality as possible? It's pretty clear that turning the quality way down while keeping the resolution at 720 results in some pretty terrible video, but I'm not sure that I should draw the conclusion that I should mostly use resolution decreases to achieve the size reduction.

**Tags:** encoding, compression

> **Comments:**
> **username_1**: The choices will partly depend on how compressed the source is to begin with. Paste the [Mediainfo](http://mediaarea.net) readout for one of your source files. Use View -> Text mode.  
> **username_2**: And what about reducing the rate down to 15 fps?  
> **username_3**: Do you have audio as well?  
> **username_0**: @Necrodeathify - yes there is a mono audio stream as well.  
> **username_4**: 10% of the original quality is not a backup, it is more like a proxy.  

---

## 3 answers

### Answer by username_5 on 2017-03-25. Score: 2

Decreasing the size a little won't help much, decreasing it a bit more induces a fair bit of aliasing (unless it smooths it also) butchering the quality without much gained.

Cutting the size 50% will reduce errors and double the jaggyness and be easily enough to save a lot of space, question is: Do you want 360P Video? You really wouldn't want any smaller.

So while that is one way to save space for Archiving I would recommend using 'Q' at 40 to test one file at 720P (output) and see if you can tolerate the quality.

H.265 has superior output quality as well as an approx. 50% reduction. Decreasing the resolution in half means an approx. 25% reduction alone, along with approx. 50% from H.265 your going to be under 15% WITH the same quality.

So decreasing the resolution from 720P will be either too drastic or induce greater errors in the output (it will begin to look like mush). Best to try using 'Q' alone as see where between 30 and 40 you can stand.

Here's an example from one particular Video YMMV.

![Compare H.264 vs. H.265 File Size](https://i.sstatic.net/JbtCt.png)

Note that going from 24 to 40 gets you down to 10% (in that one example).


---

### Answer by username_6 on 2017-03-26. Score: 1

In addition to suggestions above, you could also do a pulldown from 30fps to 24 fps.

This would likely not be noticeable to the average viewer; as 24p is the standard for film and narrative tv production.

You thus decrease the amount of discrete frames by a factor of 1/5 (20%).


---

### Answer by username_7 on 2016-07-15. Score: 0

I think just turning it in H265 will reduce it of the 10% you need. To do it well you can bring it bac to uncompeessed yuv format using ffmep then encode the yuv in HEVC using HM référence software.

> **Comments:**
> **username_1**: Why use the reference encoder? It's not well-tuned.  
> **username_0**: To be clear I mean I want the file to be 10% to 20% of the original size, hence a reduction of 90% to 80%. I think HEVC is only going to cut my file size in half at best?  

---

