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My professor was going through slides and said “Oops, that should say hdmi supported. I wrote these slides when HDMI didn’t support sound.” Is this true? I can’t find anything saying that HDMI didn’t support sound at one point

closed as off-topic by Mark, Tetsujin, Rory Alsop Nov 29 '18 at 18:45

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions that are related to consumer audio consumption (such as audiophile or home theater) are off-topic. For more information, see the meta post on Non-Production Questions." – Mark, Tetsujin, Rory Alsop
If this question can be reworded to fit the rules in the help center, please edit the question.

  • No, he probably just isn’t a tech person. – Timinycricket Nov 20 '18 at 3:38
  • I do not believe this should be closed, HDMI, and the audio portion of that is certainly a protocol used in many professional applications. I also believe that this would be a searchable question, providing reference for future queries. – Edwin van Mierlo Nov 20 '18 at 9:35
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    HDMI is a consumer protocol. The question is also a hardware question and nothing to do with sound design. – Mark Nov 20 '18 at 10:59
  • @Timinycricket It's funny that you say that. I was quite sure his statement was incorrect, but the class is called computing concepts. One of those burner plate courses that you can't get out of. I'm glad to see I've put my money to good use. smh... – Aburito Nov 20 '18 at 20:22
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I am not a true expert in this, but will try to answer this using Wiki articles. The authenticity of this answer is directly related on what trust you place in the articles.

Did hdmi ever not support audio?


TL&DR;

From Wiki information, in may be concluded that HDMI version 1.0, using standard EIA/CEA-861-B, which in turns uses CEA EDID Timing Extension data format - Version 3, did include various audio channels/codec's.

Unless your Proffessor is mentioning HDMI draft versions prior to 1.0, the statement is not correct.


1) the beginning

So we are looking for the very beginning of the HDMI standard, possibly even 1.0.

Source: https://en.wikipedia.org/wiki/HDMI

"HDMI uses the Consumer Electronics Association/Electronic Industries Alliance 861 standards. HDMI 1.0 to HDMI 1.2a uses the EIA/CEA-861-B video standard"

2) Digging into 861-B

Great, so we know that the first HDMI standards used this "861-B" thing... lets dig in.

Source: https://en.wikipedia.org/wiki/Extended_Display_Identification_Data#CEA-861-E

"The CEA EDID Timing Extension was first introduced in EIA/CEA-861, and has since been updated several times, most notably with the −861B revision (which was version 3 of the extension, adding Short Video Descriptors and advanced audio capability/configuration information)"

3) Don't you love technical details

Same source as 2, will list you some protocol details, and the various audio codec's which can be used with this standard.

[snip]

'''Audio Data Blocks''' contain one or more 3-byte Short Audio Descriptors (SADs).  Each SAD
    details audio format, channel number, and bitrate/resolution capabilities of the display as
    follows:
    SAD Byte 1 (format and number of channels):
       bit 7: Reserved (0)
       bit 6..3: Audio format code
         1 = Linear Pulse Code Modulation (LPCM)
         2 = AC-3
         3 = MPEG1 (Layers 1 and 2)
         4 = MP3
         5 = MPEG2
         6 = AAC
         7 = DTS
         8 = ATRAC
         0, 15: Reserved 
         9 = One-bit audio aka SACD
        10 = DD+
        11 = DTS-HD
        12 = MLP/Dolby TrueHD
        13 = DST Audio
        14 = Microsoft WMA Pro
       bit 2..0: number of channels minus 1  (i.e. 000 = 1 channel; 001 = 2 channels; 111 =
                 8 channels)

    SAD Byte 2 (sampling frequencies supported):
       bit 7: Reserved (0)
       bit 6: 192kHz
       bit 5: 176kHz
       bit 4: 96kHz
       bit 3: 88kHz
       bit 2: 48kHz
       bit 1: 44kHz
       bit 0: 32kHz

    SAD Byte 3 (bitrate):
      For LPCM, bits 7:3 are reserved and the remaining bits define bit depth
       bit 2: 24 bit
       bit 1: 20 bit
       bit 0: 16 bit
    For all other sound formats, bits 7..0 designate the maximum supported bitrate divided by 
    8 kbit/s.

[/snip]

CONCLUSION

From Wiki information, in may be concluded that HDMI version 1.0, using standard EIA/CEA-861-B, which in turns uses CEA EDID Timing Extension data format - Version 3, did include various audio channels/codec's.

Unless your Proffessor is mentioning HDMI draft versions prior to 1.0, the statement is not correct.

  • Why a negative vote ? Care to explain that so I can learn from it ? – Edwin van Mierlo Nov 20 '18 at 21:31
  • You're presenting rehashed wiki articles as an answer to a question that has nothing to do with sound design. No independent research other than wikipedia references. – Mark Nov 22 '18 at 3:43
  • @Mark, thank you for your opinion. Noted and will be taken into account next time. I do however question if "referencing Wiki articles" is a criteria for down-voting. I believe the answer is still very relevant to the question asked. Whether or not the question is valid is a different subject and I do have a different opinion on this. For now I will leave this answer up. – Edwin van Mierlo Nov 22 '18 at 7:02

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