Why the bitrate of encoded is the same on different scenes when rate control of H.264 is VBR.

T. J.

Other Parts Discussed in Thread: TMS320DM365

Hi,

I am using IPCAM of Appro DM368 and firmware is 1.9.0 to test VBR(IVIDEO_STORAGE) of rate control on simple scene and complex scene.

I am confused why the bitrate is the same on VBR mode of H.264 for simple scene and complex scene ?

What is the define about VBR(IVIDEO_STORAGE) of H.264 of TI ?

or

Where is the document to describe VBR(IVIDEO_STORAGE) of H.264 of TI ?

Please reference the attachment for the settings and scenes.

Thanks.

over 15 years ago

0 Anshuman Saxena over 15 years ago

TI__Mastermind 19985 points

Hi,

Please refer to Sec 3.5 of the Application Note:

Application Parameter Settings for TMS320DM365 H.264 Encoder

http://focus.ti.com/general/docs/litabsmultiplefilelist.tsp?literatureNumber=spraba9

Some more discussions on the similar topic is available at http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/100/t/32788.aspx

I hope these details should be able to give you clear understanding of the Rate Control Algo.

If you need more details, i have talked to local FAE (Edward Yao) and he can explain you the details.

Regards,

Anshuman

PS: Please mark the post as verified, if you think it has answered your question. Thanks.

0 Charles Hung over 14 years ago in reply to Anshuman Saxena

Prodigy 240 points

Hi, Anshuman

In rcAlgo parameter has another mode "Fixed-QP" algo.

Is "Fixed-QP" a kind of VBR rate control algo.?

have any document like TMS320DM365 to illustrate the "Fixed-QP" rate control Algo.?

Regards,

Charles Hung

0 Anshuman Saxena over 14 years ago in reply to Charles Hung

TI__Mastermind 19985 points

Hi Charles,

Yashwant replied the similar question on another forum post

http://e2e.ti.com/support/embedded/f/356/p/32788/244879.aspx#244879

Copying his answer in this post for completion:

"Fixed QP" means that all the frames will be coded with same QP value which is specified by the user. This option can be selected by choosing "rateControlPreset = IVIDEO_NONE" OR "rateControlPreset = IVIDEO_USER_DEFINED + rcAlgo= 2". When operating in this mode, The QP for inter and intra frame has to be provided using "intraFrameQP" and "interFrameQP" respectively.

Since RC terminologies are not standarized, people may have different interpretation. The above fixed QP in one way can be thought as VBR as the resultant of this mode will be a stream whose bitrate is varying with time.

But please note that DM36x VBR is a different RC algorithm, details of which are explained in the app note mentioned in my previous email chain.

Regards,

Anshuman

PS: Please mark this post as verified, if you think it has answered your question. Thanks.

0 Charles Hung over 14 years ago in reply to Anshuman Saxena

Prodigy 240 points

hi, Anshuman

thank you very much for your answers.

Regards,

Charles

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Why the bitrate of encoded is the same on different scenes when rate control of H.264 is VBR.