The processing delay time of HDMI Tx block of i.MX DL.

[takashitakahash]

Hi community.

Our customer has question of  the processing delay time of HDMI Tx block of i.MX DL.

<conditions:>

Audio: 2ch 48kHz sampling 16bit

And video: 800 × 480, progressive, frame rate 60fps , YUV444

  HDCP: Yes

Please see the attachmentfigure below.

※ However, if estimates of the above conditions is difficult, please tell us in the FSL specified conditions,

your reference value (theoretical value ).

[  Background Question.]

   In Apple requirements, audio output latency - (from USB video / audio packet reception, actually time until voice is output from the speaker) has been provisions.

Current situation, not be defined above is satisfied, the latency of the inside our products - we isolate the decline factor.

[igorpadykov]

Hi Takashi

unfortunately such delay time is not available, however

as rough estimation one can judge delay as calculated

from framerate in Table 34-3 supported video modes

i.MX6SDL Reference Manual (rev.2  5/2015)

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6SDLRM.pdf

Best regards

igor

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[takashitakahash]

Dear Mr Igor.

Thank you for your answers.

I understand the max processing delay time from the frame rate of the Table 34-3 within 16msec.

So, I want to know the real delay time of internal circuit (up output since the beginning of the first data to the circuit).

And it may be a rough number.

Ex  1msec or 5msec of whether 10msec ...

[qiang_li-mpu_se]

Hi Takashi, I think the delay time in HDMI transmitter should follow the HDMI specification, and it can't be changed.

For your use case, you should care the delay time between your software received the Apple video/audio data and the HDMI audio driver starts the audio data DMA. If there is sample rate convert, it will increase the delay. You can use GPIO pin to trigger the delay time, for example, when your software received the Apple video/audio data, pull that pin to high, when HDMI audio driver start the DMA, pull the pin to low, then the delay time can be captured.

[igorpadykov]

Hi Takashi

unfortunately these parameters were not characterized, sorry.

Best regards

igor