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Raise Cast Streaming mirroring to 1080p, retune bitrate range to match

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User is moving to a faster (150 Mbps) network and wants 1080p. Raised
build_video_pipeline_for_streaming and VideoParams::default() together
(they must agree -- see caststream.rs's doc comment on why a resolution
mismatch there is a protocol violation, not just soft video).

Left build_video_pipeline (the HLS/DLNA path) at 720p -- that one's
1280x720 choice is about an older Default Media Receiver's decoder
profile/level, unrelated to what's changing here.

Bitrate ceiling raised from 4-8x scaling but deliberately not straight
back up to the old 8 Mbps: real testing tonight showed the AIMD probe
pins to whatever MAX_BITRATE_KBPS is for the entire session once
estimated_bandwidth_bps() reports (unreliably -- flat ~20 Mbps most of
a session that was visibly stuttering) that there's headroom, and 8
Mbps sustained was more than the previous network+receiver could hold.
6 Mbps is a solid target for 1080p30 on its own merits. MIN_BITRATE_KBPS
bumped 1000->1500 to match (1080p needs more of a floor than 720p did
before it's a wall of blocking artifacts).
This commit is contained in:
Breadway 2026-08-06 09:25:48 +08:00
parent 1ee607b5e9
commit a058482b39
3 changed files with 38 additions and 12 deletions
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15
breadcast-core/src/pipeline/mod.rs
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@ -150,12 +150,19 @@ pub fn build_video_pipeline_for_streaming(
) -> Result<(gst::Pipeline, gst_app::AppSink, gst::Element)> {
gst::init().context("failed to initialize GStreamer")?;
// Same 1280x720@30 Main-profile baseline as build_video_pipeline, for
// the same reason (see its doc comment) -- broad decoder compatibility
// first, revisit upward once a specific device's real ceiling is known.
// 1920x1080@30 Main profile -- raised from the earlier 1280x720
// baseline (kept in `build_video_pipeline`'s HLS path, which targets a
// different, less capable receiver -- see its doc comment) once real
// hardware testing showed the actual bottleneck on the *previous*
// network wasn't resolution but the encoder being driven well past
// what that link/receiver could sustain (see `MAX_BITRATE_KBPS` in
// `breadcastd::cast_mirror`). Must stay equal to `VideoParams::default`
// in `caststream.rs` -- the OFFER's advertised resolution and what's
// actually encoded disagreeing is a protocol-level mismatch, not just
// soft video (see that struct's doc comment for what that caused).
let pipeline_str = "pipewiresrc path=%VIDEO_NODE_ID% do-timestamp=true ! \
videoconvert ! videoscale ! videorate ! \
video/x-raw,format=NV12,width=1280,height=720,framerate=30/1 ! \
video/x-raw,format=NV12,width=1920,height=1080,framerate=30/1 ! \
vah264enc name=venc bitrate=4000 key-int-max=60 rate-control=cbr ! \
video/x-h264,profile=main ! \
h264parse name=h264parse config-interval=-1 ! \