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HDMI discussion - Page 10 — Parallax Forums

HDMI discussion

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  • roglohrogloh Posts: 5,837

    @Rayman said:
    Is it just stereo with hdmi? Or do we know how to do better? Wonder how that would work..

    For now it's just two channel (stereo) audio. In theory we can generate a different audio format with up to 8 channel sources, however there are limitations in terms of sample rates and number of channels at lower resolutions that the P2 is capable of sending over DVI/HDMI. At 31.5kHz VGA line rate, we can send around 4 dual channel samples per line which is enough for 126kHz stereo audio or half that for 4 channels, or 1/3 that for 6 channels. Currently we don't really have enough P2 clock cycles per scan line to encode more than one audio packet per scan line so higher audio channel rates aren't easy to achieve at least in text modes or when any pixel doubling is occurring. Perhaps it could be done in some fixed PSRAM mode where you have more free time while you wait for the PSRAM data to arrive.

  • HDMI can do multi-channel, but that requires multiple packets per scanline (unless doing that 32k hsync trick mentioned earlier). Other problem is that which channel goes where is a bit under-specified for anything that isn't the standard 5.1 setup.

  • pik33pik33 Posts: 2,388

    I bought a RPi monitor - it has HDMI input with audio. I need some time to experiment with this and audio enabled HDMI...

    The monitor managed to display what I generate from a P2 (1024x600@50 Hz)

  • cgraceycgracey Posts: 14,206

    @pik33 said:
    I bought a RPi monitor - it has HDMI input with audio. I need some time to experiment with this and audio enabled HDMI...

    The monitor managed to display what I generate from a P2 (1024x600@50 Hz)

    That looks great! Do you have some code I could try here? I am wondering if my TV's can show this, too.

  • pik33pik33 Posts: 2,388

    https://github.com/pik33/P2-Retromachine-Basic
    This is a Basic interpreter for EC32 that use the same video driver I used in the player on the picture
    The player is here : https://gitlab.com/pik33/P2-retromachine/-/tree/main/Propeller/P2P16?ref_type=heads
    Both programs need EC32, HDMI at 0, AV at 8 and USB at 16

    @cgracey said:

    @pik33 said:
    I bought a RPi monitor - it has HDMI input with audio. I need some time to experiment with this and audio enabled HDMI...

    The monitor managed to display what I generate from a P2 (1024x600@50 Hz)

    That looks great! Do you have some code I could try here? I am wondering if my TV's can show this, too.

  • Wuerfel_21Wuerfel_21 Posts: 5,106
    edited 2024-12-15 22:06

    Also works as a small HDMI monitor: Huion Kamvas 13 pen tablet. Even has a proper 4:3 aspect ratio setting! (no idea why they'd put that in, but it makes me happy)
    Current usbnew isn't up to reading the pen data, but it does appear to use a normal HID descriptor and with some probing I can see some data changing when the pen is in range / pressed down.

  • roglohrogloh Posts: 5,837

    Neato.

    I have this 7 inch HDMI monitor running 1024x600 which I use now for some HDMI testing with the P2. I should try out MSlug on it as well sometime. It has USB mouse device support for the touchscreen IIRC and HDMI and VGA inputs plus a Headphone output.
    https://www.waveshare.com/7inch-hdmi-lcd-h-with-case.htm

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