On 2015-05-05 at 21:21, jonsm...@gmail.com <jonsm...@gmail.com> wrote: >On Tue, May 5, 2015 at 12:00 AM, kevin.z.m...@gmail.com ><kevin.z.m...@gmail.com> wrote: >> >> On 2015-04-29 at 21:20, jonsm...@gmail.com <jonsm...@gmail.com> wrote: >>>On Tue, Apr 28, 2015 at 10:37 PM, kevin.z.m...@gmail.com >>><kevin.z.m...@gmail.com> wrote: >>>> Hi, >>>> >>>> The encoder allows you to set the MaxQp(0~51), MinQp(0~51), and >>>> MaxBitrate >>>> >>>> parameters. MaxQp and MinQp are used to controlpicture quality and >>>> MaxBitrate >>>> >>>> is used to clamp the maximum encoding bit rate within the bitrate >>>> statistical >>>> >>>> time; >>>> >>>> The default configuration is MinQp = 10; MaxQp = 40. If you could not get >>>> >>>> it to work for lower bitrates , please try to change MaxQp to a bigger >>>> value, >>> >>>The bitrate setting on an h.264 encoder is supposed to take precedence >>>and be a hard limit. So if I set 500Kb/sec the encoder has to adjust >>>everything else until it can hit and hold that limit. Min/MaxQp should >>>not overrule the Bitrate limit. I believe the only exception to that >>>is for VBR where you are allowed to exceed the bandwidth limit by 10% >>>for short periods of time. The encoder is also supposed to be smart on >>>how it adjusts itself when the bandwidth limit is set. >>> >>>These limits are there for streaming video. I needed to set a 500Kb/s >>>hard limit because I only had 500Kb/s of streaming capacity available. >>>I couldn't figure out how to keep the Allwinner encoder at a 500Kb/s >>>limit, it would stay at 500Kb/s for a while but then if there was >>>rapid motion it would jump to 2Mb/s. It should not matter if CBR or >>>VBR is set, the limit should still be enforced. Of course when it >>>jumped to 2Mb/s on my 500Kb/s pipe, the stream dropped. >>> >> Nowadays, the limits of streaming video can't be controlled accurately >> with every frame, but an average in a period. On the A20 platform, it >> can't reach 500kb/s with 720p@30fps, the lowest value should be 1.5Mb/s. > >That was an important bit of information that should have been in the >datasheet. It would have saved me a huge amount of time messing with >the A20 if I had known 500Kb was never going to be possible. > > >> >>>Check out the the software x86 h.264 implementations - they will >>>output exactly 500Kb/s when told to. You can watch the picture become >>>very clear when the scene is still and then go grainy when there is >>>rapid motion. >>> >>>Also - I had severe problems with noise on A20 cameras. That noise is >>>random from frame to frame. Encoding that noise wastes all of my >>>500Kb/s bandwidth which makes the image quality terrible. Typical >>>some type of ISP is used to remove this noise before h.264 encoding. >>> >> There may be 3 main factors causing noise, they are lens, Sensor and >> ISP. A20 has none local ISP, selecting an external ISP may reduce the >> noise. Besides ISP, the lens and Sensor is important too, and the NT99141 >> is recommended. >> >>>Does the Allwinner V3 support external I2S? I'd just look in the >>>datasheet, but it is too much hassle to get it. >> Yes, V3 can support external IIS. >> We will make the documents for v3 ready as soon as possible. > >Can the V3 hit 500Kb/s for h.264? For static scenes with little noise, V3 and A83T can reach 500kbps for 720p@30pfs or 1080p@15fps.
> >Currently we are using the Grain Media GM8138S. It is very nice with >the 128MB of DRAM in the same package. We also looked at the >Highsilicon Hi3518e but it gets way too hot. We use GM8138S with >2-channel I2S. > >What we really need is: >1) 8-channel I2S V3 can support 8 channel I2S with one data wire. >2) Camera that can do low noise, 720P or 1080P video at 500Kb/s (security >video) Take reference from the above. >3) Runs Android Because V3 has no GPU, it's difficult to run a complete Android. >4) The unit is headless so no display >5) OpenCL on the GPU would be a bonus. V3 has no GPU module, can't support OpenCL. > >I have not found this combination is a low cost chip that works. > > > > ---------------- > Best Regards, > kevin.z.m > > > > >-- >Jon Smirl >jonsm...@gmail.com kevin.z.m...@gmail.com -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
