Messages in this thread | | | Subject | Re: [PATCH 4/6] media: aspeed: Support aspeed mode to reduce compressed data | From | Paul Menzel <> | Date | Mon, 18 Oct 2021 11:34:06 +0200 |
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Dear Jammy,
Am 18.10.21 um 10:51 schrieb Jammy Huang:
> On 2021/10/14 下午 02:47, Paul Menzel wrote:
>> Am 14.10.21 um 05:48 schrieb Jammy Huang: >>> aspeed support differential jpeg format which only compress the parts >> support*s* >> >>> which are changed. In this way, it reduces both the amount of data to be >>> transferred by network and those to be decoded on the client side. >> Please mention the datasheet name and revision and section, where this >> functionality is described. > > Sorry but our datasheet is confidential. The basic idea of this > feature is that we can just compress the blocks which is different > with previous frame rather than full frame. This idea is similar to > the I & P frame in multimedia. It’s still good to have the name and revision of the datasheet, the code was developed against documented. (Public datasheets would be even better, also for review.)
>> Which chips support it? > AST2400/2500/2600 all support it. >> >>> 4 new ctrls are added: >>> *Aspeed JPEG Format: to control aspeed's partial jpeg on/off >>> *Aspeed Compression Mode: to control aspeed's compression mode >>> *Aspeed HQ Mode: to control aspeed's HQ mode on/off >>> *Aspeed HQ Quality: to control the quality of aspeed's HQ mode >> Please add a space after the bullet points. >> >> Excuse my ignorance, how can these options be controlled? > > * Aspeed JPEG Format: to control jpeg format > 0: standard jpeg, 1: aspeed jpeg > * Aspeed Compression Mode: to control aspeed's compression mode > 0: DCT Only, 1: DCT VQ mix 2-color, 2: DCT VQ mix 4-color > This is AST2400 only. It will adapt JPEG or VQ encoding method according > to the context automatically. > * Aspeed HQ Mode: to control aspeed's HQ mode on/off > 0: disabled, 1: enabled > * Aspeed HQ Quality: to control the quality(0~11) of aspeed's HQ mode, > only usefull if Aspeed HQ mode is enabled
Thank you. So some sysfs file?
>>> Aspeed JPEG Format requires an additional buffer, called bcd, to store >>> the information that which macro block in the new frame is different >> s/that which/which/ >> >>> from the old one. >>> >>> To have bcd correctly working, we need to swap the buffers for src0/1 to >>> make src1 refer to previous frame and src0 to the coming new frame. >> How did you test it? What do the clients need to support? >> >> Did you test, how much bandwidth is saved? Some numbers would be nice. > I tested it by aspeed's kvm client which support decoding the aspeed > format. Currently, I am porting this feature to novnc to have openbmc > support it. Nice. > The bandwidth saved is variant. It depends on how many blocks is > different between new and old frame.If the new frame is identical > with the previous one, the compressed frame only needs 12 Bytes.
Thank you for the explanation.
Kind regards,
Paul
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