SJCAM SJ8 PRO Video Quality Is Bad For Me

Discussion in 'SJ8 Series' started by SuperMario, Aug 15, 2018.

  1. RBEmerson

    RBEmerson Humbled by events

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    I was (finally!) able to test my SJ8 with 1.2.8. If it improves something, I don't know what. Image quality remains as poor as it was when using 1.2.4. In anything less than full sunlight, paved roads show significant pixelation. Even in full sunlight, grass along the road turns into a mottled green surface with no significant detail. Objects like buildings, telephone poles and wires, trees, all show a white edge and a line of distortion following the edge. In short, image quality remains as unusable as before. The SJ7 V1.15 remains the high water mark for the SJ7/SJ8 series of cameras.
     
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  2. Derg

    Derg New Member

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    hallo,
    next problem.
    I would like to show you my 1080p 60 video. link:
    https://www.youtube.com/watch?v=xMnn...ature=youtu.be
    I have problem, when gyro is turned on. The video has a vibration (shakes,jump) effect from
    time to time. I have a question for you. Can you check in yours
    sj8pro at 1080p 60 with fast horizontal motion like in my
    video. Is this efect in your camera also? I do not know if this is a software or camera problem.
    Look at the trees.
     
    Last edited: Dec 13, 2018
  3. kamkar

    kamkar Elite

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    Did you just record in 720p/60 ?
    Thats silly with a camera like this, thats like buying a BMW car and only use 1 and 2 gear.

    It is also best if you provide a link so people can Dl the raw video, youtube re-compress video footage and it often ens up as a mess.
     
  4. Derg

    Derg New Member

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    The original video is 1080 60p, gyro on and it looks the same as it from you tube.
    This is probably a "sports camera."
    When making a dynamic viedeo (alpine skiing for example) you need a minimum of 60p, 60 fps and gyro is available only 1080. 30 fps can be done in portrait scenes.
    I present here how horribly gyro works in this camera with fast horizontal movements.
    This BMW has a lot of problems with correct work.
    See how correction distortion works.
    "Can you check this problem on your camera?:
    I would like to show you the problem that I have in my camera (1080P 60). When the correction is on, there is a large video distortion on the left and right side of the image (rolling). From up to down. I have a question for users. Is this issue in your cameras?"
    https://drive.google.com/file/d/1C3lOry9cbTDwI1HgizBK2gMEN-y7Wqs0/view
     
  5. RBEmerson

    RBEmerson Humbled by events

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    Distortion correction: I see this "feature" as mostly for bragging rights. My camera does something you camera doesn't do,,, nyah, nyah, nyah. Distortion correct is something best left for post production. That's a lot of data to rearrange in real-time with limited time to do any work, and limited computing horsepower. In post, there's no need for real-time processing, and more computing power can be used to avoid the artifacts you're seeing. In short, be happy you get something usable at all.

    Electronic Image Stabilization (EIS) design has to chose between being stable in two axis, vertical and horizontal. Let EIS work in both axis and motion will jump in either direction as the EIS stabilizes the image until it can't work on the scene. The scene then lurches to the point where the EIS can't work on the scene, lurch... wash, rinse, repeat.

    Most objectionable motion is vertical: bouncing up and down. Reduce the amount of stabilization in horizontal motion and smooth panning is easy, even when the camera is bumping up and down.

    But add distortion correction on top of EIS and the small jerks you're seeing are no surprise.
     
  6. Sauron

    Sauron New Member

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    Hmm so you are saying we/I should not use both image stabilization and distortion correction? I was assumed all this stuff is HW specific and CPU has build in this feature - so it's not something SJ is programming by themselves in firmware.
     
  7. RBEmerson

    RBEmerson Humbled by events

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    Simply put, there's only you can reasonably expect from a small camera with limited resources. As I said earlier, things like lens correction are best left to post production. Stability is a requirement for having good footage to work with in post. so, pick one or the other, but forget both.
     
  8. kamkar

    kamkar Elite

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    Or if you really have to as we say here " blow and have a mouthful of flour at the same time " then you must fit a lens with no wide angle side affects.
    BUT ! then i am not so sure EIS will work properly.

    I would do post production dewarp, not least since my editing suite have default profiles for different action cameras though as i recall none of then are SJcam, so i would have to create one which should not be that bad to do.

    I am a little turned on to the new Dji osmo pocket, only its AF seem a bit slow as it is now, but maybe firmware can resolve that.
    I don't do much on board action but a some times film "action" from a distance, the the little Dji osmo pocket and 4K60 and gimbal stabilized are really tempting for me.
    Need good daylight performance.

    I did order the SJ8 pro but had to return it, and i did have a plan for getting a gimbal for it too. but now both of those ideas are on the back burner if not totally off.
     
  9. RBEmerson

    RBEmerson Humbled by events

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    Probably EIS will still be usable. It samples the edge of the frame to figure out the direction and amount of change. As long as the added lens' esulting image fills the sensor, the added lens shouldn't cause any EIS problems. IMHO ;)
     
  10. Sauron

    Sauron New Member

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    We are drifting from the topic a bit.. :) But you've lost me.
    SJ8 pro is advertised as "Inner Six-Axis Gyroscope" - so I've assumed so far, this 'so called' gyroscope is used to measure tilt in every direction and CPU corrects video by moving/tilting each frame accordingly. So this is not true image sensor stabilization where sensor is moved to stabilize video.
    What you are describing RB - is plain software stabilization, based on image analyse. Am I missing something?
     
  11. kamkar

    kamkar Elite

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    I think the 2 cancel each other out on the hardware used in the SJ8pro, and in the SJ7 star i have too, not aware if that can be done on other more expensive cameras.

    If the sensor are moved around i think it is OIS ( optical image stabilization ) as in some Sony cameras, and phones ASO nowadays, the Sj cams just have EIS ( Electronic Image Stabilization ) and so can only do this with lesser resolutions than the sensor max.
    So the camera chase a 1080p image from the middle of the sensor around on a 4-5-6K sensor, and put those in line as the output file.
    The 4K30 EIS the SJ8 pro can do is the same it just chase a 4K / 8 mpix image around on the 12 mpix sensor, the missing 4K60 EIS i assume are down to the calculative powers of the SOC.
     
  12. RBEmerson

    RBEmerson Humbled by events

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    Um... 6-axis gyro is sort of a marketing slight of hand trick coupled to a nice engineering trick. There are three axis of motion: pitch, yaw, roll. It's tough to beat three primary axis. The three other axis aren't axis of motion, they're accelerometers that sense motion in the three axis. That is, they detection motion along one of the three axis. They don't detect pitch, roll, and yaw (that's the gyro's job), but that gyro is being pushed or pulled on some combination of the three axis. If SJCam claims they use one, sobeit. Since the camera imagery is miserable, I can't be sure about how well the EIS is working. I can't say as I've seen anything that approaches the Sony FDR-X3000's (my current action cam) stability. See a demo of OIS and EIS, EIS alone, and no IS below. If the SJ8 can match the "EIS only" demo, it's doing well enough.

     
  13. RBEmerson

    RBEmerson Humbled by events

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    IIRC, the SJ7 is supposed to have some sort of gyro, too. Or so it says somewhere....
     
  14. kamkar

    kamkar Elite

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    yes but don't the gyro just aid the EIS system, maybe making it a little better,
    Otherwise i cant see what the gyro are for unless it is for logging like GPS do speed in a dashcam.
    I have seen footage from other cameras that have a slew of sensors and allow for their data to be overlain the recording in post, but i always found it silly, and its not something i would use myself other for a possible documentation issue in relation to dialing something in.
    Like say amount of G in a corner as you dial your track day car in and you try different setups.

    I couldn't car less that some guy in his Italian racer pull 0.92G in so and so corner, it only have a interest for me if i can get to do it myself.
     
  15. Sauron

    Sauron New Member

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    Yes, gyroscope and accelerometer aka 6 axis gyro ;) - are to measure movement of camera (direction and acceleration) so CPU can stabilize video in real time knowing how to process each frame (where to crop, how to shear or skew). This type of stabilization is much more efficient then software image analyse stabilization (the only stabilization you can do in post process) - but probably less efficient then optical/physical image stabilization (OIS) for shaking - where sensor or lenses are physically moved against camera movement to stabilise video.
    Gyro+EIS theoretically (I'm not sure how it's utilized in SJ8P) has this advantage over OIS - that it can stabilize not only X/Y movement (shaking in plane of sensor) but also pitch and yaw movement - because it has necessary information.
     
  16. RBEmerson

    RBEmerson Humbled by events

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    Well (old saying) the proof of the pudding (EIS like OIS) is in the eating. I'm still waiting for SJ8 pudding.
     
  17. Sulev Svilponis

    Sulev Svilponis Elite

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    If the replacement lens has very different focal length, then the EIS might not be able to handle, how fast the image edge is moving because of camera shaking. The longer the focal length is, the smaller shake of the camera is causing too large shift of the image on the sensor level for EIS to handle.
     
  18. Aleksandrs Bazilevics

    Aleksandrs Bazilevics New Member

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    It's made to shoot in 4k... That's what they set up anyway. Sad, that other record options left without any attention.
    About EIS I'm not really sure if it's working...
     
  19. Aleksandrs Bazilevics

    Aleksandrs Bazilevics New Member

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  20. RBEmerson

    RBEmerson Humbled by events

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    Beats me about EIS in the clips. I'm inclined to think it's not working. The best test is to anchor the camera on something; keep the camera from bouncing around on its mount. Shoot 4K and then 1080 for a comparison.
     

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