Video compression app

[sako243]

Sounds like you just need more storage .

Out of curiosity you say you've achieved 50% compression. So you're saying the video that was 2 minutes long that was stored on your phone occupying 440MB you've managed to get down to 220MB without any loss of information? Call me a skeptic but how?

I've not looked into the depths of H.264 but am broadly familar with the techniques as I've spent quite a lot of time involved with RF and signals analysis. I'm genuinely interested in how you achieved a further 50% on top of the 98% already achieved.

 

[grim_d]

@sako243

Yes, more storage would be lovely, 64GB isn't enough for your phone these days if you have young kids! I was looking at upgrading to the 4a when it comes out.....64GB non expandable

To be clear I'm not saying it's achievable with no loss of information, I'm not achieving the impossible or claiming so.

Broadly, h.264 is considered "lossless".... wether an app is using a lossy technique, altering the bitrate or downscaling, or all of the above, I can get them to about 50% of their original size with no perceptible (on my phone, to my eyes), loss of quality.

Even at the same resolution, bitrate and lossless compression some apps are able to achieve 15% compression on the original, how? No idea, some sneaky techniques likely.

I didn't want it to be a technical topic, that's really boring.

 

[mtt.tr]

Pay monthly for google storage, i store nothing on my phone

 

[sako243]

Broadly, h.264 is considered "lossless"

I understand you've put it in quotes but I've yet to meet anything or anyone that refers to H.264 as lossless. From the first paragraph of the Wikipedia article on it:

H.264 is typically used for lossy compression, although it is also possible to create truly lossless-coded regions within lossy-coded pictures or to support rare use cases for which the entire encoding is lossless.

I can get them to about 50% of their original size with no perceptible (on my phone, to my eyes), loss of quality

That is the crucial bit - you are most likely losing information in here.

Even at the same resolution, bitrate and lossless compression some apps are able to achieve 15% compression on the original, how? No idea, some sneaky techniques likely.

It may not be sneaky techniques at all just bloody clever ones. The raw data rate produced by modern cameras can realistically only be handled by RAM, even SSDs struggle to keep up with it. My example previous at 30fps 1080p is generating 178MB/s. Up that to the more commonly available 4K resolution of 3840x2160 at 60fps and you're generating data at ~1.4GB/s. Now I've got a fairly punchy SSD in my desktop and that will do ~550MB/s sustained on it's own so you will have to stripe the data in RAID just to get it to disk.

What was the point of that exercise? Well simply put your phone can't deal with 1.4GB/s to Flash or a micro SD card, it's just beyond it, so you've got no option but to compress it straight off the camera. It's unlikely that modern phones / cameras that shoot 4K natively will offload this to the processor there'll either be a dedicated chip or the processor may have a hardware based encoder built into it. If you think about the requirements for such a chip - it's to handle real-time capture of that data, whatever happens you have to be able to write the video to storage slightly faster than you are producing it. You can't stutter or pause for a second because you'll run out of buffering very quickly. My brief research into H.264 shows that there are many different possibilities for encoding the same data (at the same rate of "lossiness") in a variety of ways but they all have a cost associated with them - that will either be RAM / buffering requirements, processing time etc. The implementation on the hardware chip will have been optimised for a consistent latency through the device - i.e. you put in a frame of data and x number of frames later a compressed one comes out at a consistent rate. That way you can guarantee that you have continuous, real-time encoding of the video so you can design your storage requirements around it.

The apps that you have tried don't necessarily have the same requirement - they are "offline" and as such they can use as much memory as they want or is available and take as long as they want. The last point is the crucial bit, taking longer. One of the techniques used by H.264 is that you keep key-frames and then simply output the differences from the previous one, a decided chip on an embedded platform can only hold so much information in order to compute the changes required for the compression algorithm. Processing off-line who cares if you spent 5x, 10x, 1000x, a million times longer to look up a frame from 30s ago because the algorithm's worked out most of the frame is static so doesn't change that much. The real-time implementation can't make that assumption.

OK - that was a slightly long winded way of explaining that basically the "offline" compressors can spend time searching avenues that are not worthwhile and discarding the results. The raw capturing from the camera app is unlikely to be able to do the same thing. My guess is that you're unlikely to find a better app that captures at a higher compression rate while you video, this is all a bit of a guess from me but I doubt that the app has much control over how it's compressed - it'll just be given an encoded data stream which can be saved to disk directly or it can pass it through to the display driver which will decode it in hardware again. I.e. the app is just the post-man to a certain extent passing data around, he can't control what's inside it.

Having said all that I expect that there are some options that can be tweaked in the hardware encoder by the app - I have no idea whether they're accessible but if you don't want to change your camera app then I don't think you can do much about it.

 

[grim_d]

@sako243

It's important to note that lossy and lossless refer to the format and not the compression, just like .MP4 is a container and not a compression type though I'm quite confident you are aware of that.

Saying h.264 is "lossless compression" is a misnomer, it doesn't make sense by definition as it is a lossy algorithm, but it does to the average consumer. Semantics....who was it that enjoyed them? @slim_boy_fat ?

This is where is gets too technical for this thread and what I was trying to avoid, mostly because I'm uneducated and frankly, uninterested...no disrespect. It's for that exact reason I left all this behind at college and uni.

I feel like the point and my aim has been missed somewhat, which is fine because my question has been answered.

 

[slim_boy_fat]

Semantics....who was it that enjoyed them? @slim_boy_fat ?

I'm just an innocent bystander on this one, I know less than the square root of bugger all about such things + elektrickery....

 

[sako243]

I feel like the point and my aim has been missed somewhat, which is fine because my question has been answered.

That is fair enough. Was just trying to point out why I don't think you'll find an app that will do what you want

 

[grim_d]

That is fair enough. Was just trying to point out why I don't think you'll find an app that will do what you want

We didn't even get onto the metadata!

 

[sako243]

 

[Kayos]

What's all this compression stuff? I shoot and save everything in raw, photos are converted to dng but only because it's an open standard so (in theory) should always be able to access them

I pay for unlimited Flickr, even with 200k photos and gawd knows how much video it always shows as 1% of unlimited

As for the question, if you have a modern phone is it worth it? Keep the originals safe, upload to youtube and watch them on auto resolution when needed

 

[sako243]

What's all this compression stuff? I shoot and save everything in raw, photos are converted to dng but only because it's an open standard so (in theory) should always be able to access them

Photos are a completely different ball game, your not dealing with anywhere close to the same amount of data.

Anyway @grim_d appears to have his answer.

 

[Kayos]

Photos are a completely different ball game, your not dealing with anywhere close to the same amount of data.

Anyway @grim_d appears to have his answer.

I only mention photos because I know what I have, 40mb per shot or upto 2GB for a large negative scan

Video is also as raw as my camera will give me, just updated my second nas to 12tb as the 8tb was getting full