Ultra-wide monitor support - Screen resolution, Video and Audio Raspberry Pi 4 B

Question

Ultra-wide monitor specs: 34 inch WHFD (2560 x 1080) IPS Display (21:9) - HD 10 AMD Free sync

OS: Arch linux with Openbox (lightdm)

Issues:

1. Managed to get 2560x1080 pixels with hdmi_enable_4kp60=1 in /boot/config.txt but the default DPI is less meaning that text and icons are too small.
2. When playing video in full screen mode with aspect ratio beyond 720p , it's not smooth as if its skipping frames but still plays, but plays smoothly when played at 720p or below.
3. No audio over HDMI, not sure what I am missing in config.txt

Required information given below, please ask any addition info needed. Thank you in advance :)

[xxx@archlinux ~]$ xdpyinfo | grep -B2 resolution

1. screen #0:
2. dimensions: 2560x1080 pixels (677x286 millimeters)
3. resolution: 96x96 dots per inch

/boot/config.txt :

1. gpu_mem=512
2. initramfs initramfs-linux.img followkernel
3. kernel=kernel8.img
4. arm_64bit=1
5. device_tree=broadcom/bcm2711-rpi-4-b.dtb
6. enable_gic=1
7. dtparam=audio=on
8. hdmi_drive=2
9. hdmi_enable_4kp60=1
10. disable_overscan=1

Answer 1

Have you attempted this? It apparently works for the 3B+. These settings go in /boot/config.txt

# uncomment to force a specific HDMI mode (this will force VGA)
hdmi_timings=2560 0 48 32 80 1080 0 7 20 12 0 0 0 52 0 159838855 7
hdmi_group=2
hdmi_mode=87
hdmi_drive=2
framebuffer_width=2560
max_framebuffer_width=2560
framebuffer_height=1080
hdmi_pixel_freq_limit=160000000

Source: https://www.reddit.com/r/raspberry_pi/comments/aywsn2/configuration_settings_for_ultrawide_2560x1080/