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