Rare Android tablet displays video - hen's teeth
Posted 21 June 2013 - 01:01 AM
It is a big surprise. It works!
I'll describe this tablet as much as I can dig it out.
First, don't rush out to buy one until you think it through and understand what to buy (multiple configurations w/ tradeoffs) ....
You have seen a 7" Android tablets available for sale from many online eTailers with very low price ($50 - $120). The device I bought is similar with them with "special" tweaks. Mine is special-tailored for car navigation. Moreover, you need to make sure it is the one with AV-IN option. Go to aliexpress.com and search for
7" android gps navigator av-in.
Before you click the "buy" button, please understand few key drawbacks:
- They are all unbranded with various hardware (some high end and some very low end). This makes selection very difficult. Price ranges from $90 to $150.
- Many come with free GPS navigation software (with various glitches, e.g., I couldn't get mine to work with the voice announcement, LCD screen is not very bright for bright daylight driving.)
- On its video display (AV-IN), it takes in composite video RS-170A feed through special 2.5mm 4-ring video cable. It is wide screen format (stretched horizontally, circle is an ellipse) only. There is no commonly used brightness, contrast adjustment easily accessible as would be seen in a regular video monitor. AV-IN cable is sold separately.
- Even the pricey ones ($150) are not using the high-end Android hardware spec. With Android 4.0 loaded, it is usable but probably you would not want to brag about it.
- Shall I say, this device is thick (fat).
- Charge the batt first. Do not power on immediately. Disconnect the power (mini USB connector) first, then turn it on to let it go through the initialization process.
Now a little bit details on the device:
- It is mainly designed for in-vehicle applications (car navigator, car DVR - to record the road driving or meteor falling using Android's front camera, and vehicle backup camera <-- AV-IN fed with a backup video camera.)
- You can use Android's screenshot to capture what's on the screen, including the video being displayed. This is not video recording, but capture the current scene (e.g., long exposure astro video image.) After the capture, you can use Android email (e.g., Gmail) to WiFi send the pic to email destinations.
- AV-In cable is a 2.5mm 4-ring plug. Last ring is ground, the one next to it is the composite video in. If a valid video signal is present, Android's current screen will disappear in 3 seconds and video shows up. There is no special app to run. Remove the video signal or unplug the AV-IN plug, the regular Android screen returns. (Mine does not come with the AV cable. I custom made my own.)
- Do not trust what's stated in the package box, it's a fixed design. Don't trust the user manual either (due to fixed design.) Mine does not come with any manual/instruction!
- Almost all are using a single core ARM processor (ignore the hype of virtual dual core). Mine is Allwin A13 single-core 1GHz Cortex A8 architecture/ARM v7 rev 2, with Mali 400MP, one core GPU. This is why Android ICS 4.0.4 is so sluggish. Also, 1080p playback may be okay-ish. 2160P, forgetaboutit.
- The board is "nuclear" and the device is "nuclear-puppis".
- It has 512MB RAM and 8GB flash (512M flash is allocated as the main.) This is okay-ish. I have seen very low spec (e.g., 128MB RAM and 2GB flash) you'll regret it.
- Mine has GPS (naturally ), 2.4GHz band only WiFi, no cellular modem, no Bluetooth. It has a 3-axis accelerometer, no gyro (<-- very beneficial, prefer to have), no magneto compass, no real tilt sensor (simulated with accelerometer.)
- It does not have a real ambient light sensor.
- It has a TF card slot, internal mic, internal speaker, headphone out, front camera (1600x1200) without LED lighting assist, and back camera (640x480).
- It has a capacitive touchscreen (at least two-finger gesture works). Do not buy low-end using resistive touchscreen! LCD resolution is 800x480 wide format. Do not buy lower resolution LCD.
- There is only one hard button: this power button. More would be nicer.
- There is a FM transmitter for audio. Not so useful.
- Battery is ??? mAh (may be LiFe.) Note there are all kind of variations (2000 - 4000mAh) on these devices.
- Come with car mount and DC charger. Mine does not have an AC charger for some reasons.
- Does it support OTG? Not yet tested.
- Mine is Android 4.0.4. Do not use Android 2.x device. I've seen similar devices but the OS is WinCE (also with low spec.), not recommended.
- Use the free app "Screenshot Ultimate" to do screenshot.
- In my device, the navigator is iGO (need to inform teh seller the country-specific map), and the DVR software (only for on-board front camera) is DailyRoads Voyager.
- Came already rooted.
Posted 21 June 2013 - 01:36 AM
Just a problem, for me, is the brightness of the monitor that cause the deep sky live view a bit brighter, so the background isn't as dark as it should be. Better, it would be better to power up contrast monitor.
I tried an app called screen adjuster to set the tablet monitor. Yes, it works for brightness because you can dim the monitor brightness up to 85% below minimum system brightness, but you can't properly set the contrast up: you can just set the contrast down from 0 to -180.
So i couldn't find an app that sets the contrast and brightness at the same time correctly as i'd like (especially contrast up and not just down below 0)...
ccs_hello, i'm waiting your digging out from this tablet: i'm pretty sure you can do it and experiment everything possible on this toy...maybe you'd be able to find the correct app to set brightness and expecially contrast in a right way...
Posted 21 June 2013 - 08:28 PM
- It appears that the datapath is indeed aware/managed by Android.
- Video display is controlled by an app "cramer" and there is a process "reverse service" (means vehicle's gear is in back up).
- In video display, screen update rate may be around 5 - 15 fps. Did not find a video recording program (will slow refresh rate further anyway.)
- Its LCD glass does not have as good quality as SONY's 970. Colors appears to be fading and definitely not as vibrant.
- Also, multiburst pattern video capture here.
- If the screen is upside down or turned 90 degrees, touch the LCD screen to rotate it back.
- When video display is running, press "power" hard button to gain Android toolbar. You can run other applications as well as seeing the app "cramer" at work.
Posted 22 June 2013 - 08:16 AM
(must pick capacitive screen and AV-IN option)
P.S. as a general rule, if the product spec does not state capacitive, your'll get low spec. resistive touch screen. Same for other components.
No affiliation with the seller.
Posted 23 June 2013 - 02:00 PM
Posted 06 September 2013 - 06:55 AM
The tablet I tried is using Allwinner A13 SoC (System on Chip), not so fancy and fast. Most likely, it has a GM7113 (clone of SAA7113) analog video decoder pumping out CCIR656 digital video to SoC's parallel video input interface.
Also note the tablet's camera module when configured to streaming out video, is using some forms of digital video format, displayed by "Camera" app at high(er) refresh rate.
One might ask why the "Cramer" app has limited refresh rate and no recording capability when compare with "Camera" app? Cannot tell for sure, but here is a possible hint:
In a different tablet using a different SoC (Rockchip RK3088), the data brief sheet of RK3088 stated that it has digital video's parallel input port. It should be the port taking in CCIR656 digital video.
However, there is a good indication that it is the GPU part of the SoC that is taking in digital video, not CPU part of SoC (these CPUs are all are ARM based). <-- makes sense since the CPU is not designed to be I/O centric and I/O intensive. As we all know, GPU part of the code is closed-sourced and proprietary.
So for now, the door is closed.
Important to note that
feeding uncompressed digital video (CCIR 656 4:2:2) through USB interface to this type of (under-powered) tablet is a bad idea. It wouldn't have the bandwidth nor CPU power to handle the streaming, high data rate video.
P.S. this tablet's OTG port works (flash drive, etc.)
P.S.2 Raspberry Pi's CSI-2 (Camera System Interface), a very high speed serial interface, to connect to Pi's camera module, also direct feed BCM2835 SoC's GPU.
Posted 12 October 2013 - 09:12 PM
With GM7113 (cloned SAA7113) as the video frontend, I did see some color artifacts. (Lady's hairs, man's face, ...)
(Link removed. If you'd like to see it, pls PM.)
Posted 12 October 2013 - 09:12 PM
(Link removed. If you'd like to see it, pls PM.)