Comment 6 for bug 1910537

I have same device ATEM Mini Pro ISO and Dell Vostro 3450.
I can confirm, that bug exists and is possible to grab sound from only first port.

Actually all ports on ATEM HDMI grabber are NOT same. HDMI1 is using different hardware than all others and is accepting sound from my computer.
If I'm using HDMI2,3,4 port - then yes, no sound.

To help debug problem, here is ATEM Mini Pro ISO teardown report with chip ID's for all ports - https://wphost.spider-e.com/?p=940

And here EDID report with connected HDMI1 and HDMI2:

//HDMI1
sudo get-edid -b 5 | edid-decode
This is read-edid version 3.0.2. Prepare for some fun.
Attempting to use i2c interface
Only trying 5 as per your request.
256-byte EDID successfully retrieved from i2c bus 5
Looks like i2c was successful. Have a good day.
edid-decode (hex):

00 ff ff ff ff ff ff 00 23 01 00 00 01 00 00 00
26 10 01 03 80 47 28 96 0a da ff a3 58 4a a2 29
17 49 4b 00 00 00 01 01 01 01 01 01 01 01 01 01
01 01 01 01 01 01 02 3a 80 18 71 38 2d 40 58 2c
45 00 c4 8e 21 00 00 1e 02 3a 80 d0 72 38 2d 40
58 2c 45 00 c4 8e 21 00 00 1e 00 00 00 fc 00 42
4d 44 20 48 44 4d 49 0a 20 20 20 20 00 00 00 fd
00 32 3c 1f 44 08 00 0a 20 20 20 20 20 20 01 f7

02 03 1f 54 49 85 84 94 93 a0 a1 a2 9f 90 23 09
04 07 83 01 00 00 68 03 0c 00 10 00 00 1e 00 01
1d 00 72 51 d0 1e 20 6e 28 55 00 c4 8e 21 00 00
1e 01 1d 00 bc 52 d0 1e 20 b8 28 55 40 c4 8e 21
00 00 1e 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f2

----------------

EDID version: 1.3
Manufacturer: HXA Model 0 Serial Number 1
Made in week 38 of 2006
Digital display
Maximum image size: 71 cm x 40 cm
Gamma: 2.50
RGB color display
First detailed timing is preferred timing
Color Characteristics
  Red: 0.6396, 0.3447
  Green: 0.2910, 0.6347
  Blue: 0.1630, 0.0927
  White: 0.2880, 0.2958
Established Timings I & II: none
Standard Timings: none
Detailed mode: Clock 148.500 MHz, 708 mm x 398 mm
               1920 2008 2052 2200 ( 88 44 148)
               1080 1084 1089 1125 ( 4 5 36)
               +hsync +vsync
               VertFreq: 60.000 Hz, HorFreq: 67.500 kHz
Detailed mode: Clock 148.500 MHz, 708 mm x 398 mm
               1920 2008 2052 2640 ( 88 44 588)
               1080 1084 1089 1125 ( 4 5 36)
               +hsync +vsync
               VertFreq: 50.000 Hz, HorFreq: 56.250 kHz
Display Product Name: BMD HDMI
Display Range Limits
  Monitor ranges (GTF): 50-60 Hz V, 31-68 kHz H, max dotclock 80 MHz
Has 1 extension block
Checksum: 0xf7

----------------

CTA-861 Extension Block Revision 3
Basic audio support
Supports YCbCr 4:2:2
4 native detailed modes
27 bytes of CTA data blocks
  Video Data Block
     1920x1080i 60.000 Hz 16:9 33.750 kHz 74.250 MHz (VIC 5, native)
     1280x720 60.000 Hz 16:9 45.000 kHz 74.250 MHz (VIC 4, native)
     1920x1080i 50.000 Hz 16:9 28.125 kHz 74.250 MHz (VIC 20, native)
     1280x720 50.000 Hz 16:9 37.500 kHz 74.250 MHz (VIC 19, native)
     1920x1080 24.000 Hz 16:9 27.000 kHz 74.250 MHz (VIC 32, native)
     1920x1080 25.000 Hz 16:9 28.125 kHz 74.250 MHz (VIC 33, native)
     1920x1080 30.000 Hz 16:9 33.750 kHz 74.250 MHz (VIC 34, native)
     1920x1080 50.000 Hz 16:9 56.250 kHz 148.500 MHz (VIC 31, native)
     1920x1080 60.000 Hz 16:9 67.500 kHz 148.500 MHz (VIC 16, native)
  Audio Data Block
    Linear PCM, max channels 2
      Supported sample rates (kHz): 48
      Supported sample sizes (bits): 24 20 16
  Speaker Allocation Data Block
    Speaker map:
      FL/FR - Front Left/Right
  Vendor-Specific Data Block, OUI 0x000c03 (HDMI)
    Source physical address 1.0.0.0
    Maximum TMDS clock: 150 MHz
Detailed mode: Clock 74.250 MHz, 708 mm x 398 mm
               1280 1390 1430 1650 (110 40 220)
                720 725 730 750 ( 5 5 20)
               +hsync +vsync
               VertFreq: 60.000 Hz, HorFreq: 45.000 kHz
Detailed mode: Clock 74.250 MHz, 708 mm x 398 mm
               1280 1720 1760 1980 (440 40 220)
                720 725 730 750 ( 5 5 20)
               +hsync +vsync
               VertFreq: 50.000 Hz, HorFreq: 37.500 kHz
Checksum: 0xf2

//HDMI2
sudo get-edid -b 5 | edid-decode
5
This is read-edid version 3.0.2. Prepare for some fun.
Attempting to use i2c interface
Only trying 5 as per your request.
256-byte EDID successfully retrieved from i2c bus 5
Looks like i2c was successful. Have a good day.
edid-decode (hex):

00 ff ff ff ff ff ff 00 23 01 00 00 01 00 00 00
26 10 01 03 80 47 28 96 0a da ff a3 58 4a a2 29
17 49 4b 00 00 00 01 01 01 01 01 01 01 01 01 01
01 01 01 01 01 01 02 3a 80 18 71 38 2d 40 58 2c
45 00 c4 8e 21 00 00 1e 02 3a 80 d0 72 38 2d 40
58 2c 45 00 c4 8e 21 00 00 1e 00 00 00 fc 00 42
4d 44 20 48 44 4d 49 0a 20 20 20 20 00 00 00 fd
00 32 3c 1f 44 08 00 0a 20 20 20 20 20 20 01 f7

02 03 1f 54 49 85 84 94 93 a0 a1 a2 9f 90 23 09
04 07 83 01 00 00 68 03 0c 00 20 00 00 1e 00 01
1d 00 72 51 d0 1e 20 6e 28 55 00 c4 8e 21 00 00
1e 01 1d 00 bc 52 d0 1e 20 b8 28 55 40 c4 8e 21
00 00 1e 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 e2

----------------

EDID version: 1.3
Manufacturer: HXA Model 0 Serial Number 1
Made in week 38 of 2006
Digital display
Maximum image size: 71 cm x 40 cm
Gamma: 2.50
RGB color display
First detailed timing is preferred timing
Color Characteristics
  Red: 0.6396, 0.3447
  Green: 0.2910, 0.6347
  Blue: 0.1630, 0.0927
  White: 0.2880, 0.2958
Established Timings I & II: none
Standard Timings: none
Detailed mode: Clock 148.500 MHz, 708 mm x 398 mm
               1920 2008 2052 2200 ( 88 44 148)
               1080 1084 1089 1125 ( 4 5 36)
               +hsync +vsync
               VertFreq: 60.000 Hz, HorFreq: 67.500 kHz
Detailed mode: Clock 148.500 MHz, 708 mm x 398 mm
               1920 2008 2052 2640 ( 88 44 588)
               1080 1084 1089 1125 ( 4 5 36)
               +hsync +vsync
               VertFreq: 50.000 Hz, HorFreq: 56.250 kHz
Display Product Name: BMD HDMI
Display Range Limits
  Monitor ranges (GTF): 50-60 Hz V, 31-68 kHz H, max dotclock 80 MHz
Has 1 extension block
Checksum: 0xf7

----------------

CTA-861 Extension Block Revision 3
Basic audio support
Supports YCbCr 4:2:2
4 native detailed modes
27 bytes of CTA data blocks
  Video Data Block
     1920x1080i 60.000 Hz 16:9 33.750 kHz 74.250 MHz (VIC 5, native)
     1280x720 60.000 Hz 16:9 45.000 kHz 74.250 MHz (VIC 4, native)
     1920x1080i 50.000 Hz 16:9 28.125 kHz 74.250 MHz (VIC 20, native)
     1280x720 50.000 Hz 16:9 37.500 kHz 74.250 MHz (VIC 19, native)
     1920x1080 24.000 Hz 16:9 27.000 kHz 74.250 MHz (VIC 32, native)
     1920x1080 25.000 Hz 16:9 28.125 kHz 74.250 MHz (VIC 33, native)
     1920x1080 30.000 Hz 16:9 33.750 kHz 74.250 MHz (VIC 34, native)
     1920x1080 50.000 Hz 16:9 56.250 kHz 148.500 MHz (VIC 31, native)
     1920x1080 60.000 Hz 16:9 67.500 kHz 148.500 MHz (VIC 16, native)
  Audio Data Block
    Linear PCM, max channels 2
      Supported sample rates (kHz): 48
      Supported sample sizes (bits): 24 20 16
  Speaker Allocation Data Block
    Speaker map:
      FL/FR - Front Left/Right
  Vendor-Specific Data Block, OUI 0x000c03 (HDMI)
    Source physical address 2.0.0.0
    Maximum TMDS clock: 150 MHz
Detailed mode: Clock 74.250 MHz, 708 mm x 398 mm
               1280 1390 1430 1650 (110 40 220)
                720 725 730 750 ( 5 5 20)
               +hsync +vsync
               VertFreq: 60.000 Hz, HorFreq: 45.000 kHz
Detailed mode: Clock 74.250 MHz, 708 mm x 398 mm
               1280 1720 1760 1980 (440 40 220)
                720 725 730 750 ( 5 5 20)
               +hsync +vsync
               VertFreq: 50.000 Hz, HorFreq: 37.500 kHz
Checksum: 0xe2