From 4c180c428bb64016e242242786391976fcfe9acd Mon Sep 17 00:00:00 2001 From: Amit Prakash Ambasta Date: Tue, 26 May 2026 19:55:40 +0530 Subject: [PATCH] fix(screencast): advertise 8-bit SHM fallback formats for non-10-bit-aware consumers When the compositor uses a non-8-bit render format (e.g., XRGB2101010 on 10-bit panels), PipeWire link negotiation fails because the only SHM format advertised is xRGB_210LE, which SHM-only consumers like Firefox don't support. The 8-bit formats (BGRA/BGRx) are only offered with mandatory DMA-BUF modifiers, making them unreachable for these consumers. Advertise ARGB8888/XRGB8888 as additional no-modifier SHM format pods when they appear in the DMA-BUF format list but not in the SHM list. Update buffer creation to compute stride for these fallback formats. Also fix a type mismatch in build_formats() that iterated the shm_formats array (struct xdpw_shm_format, 8 bytes) with a uint32_t pointer (4-byte stride). Fixes: screenshare with Firefox on 10-bit displays Signed-off-by: Amit Prakash Ambasta --- src/screencast/pipewire_screencast.c | 37 +++++++++++++++++++++++++--- src/screencast/screencast_common.c | 19 ++++++++------ 2 files changed, 46 insertions(+), 10 deletions(-) diff --git a/src/screencast/pipewire_screencast.c b/src/screencast/pipewire_screencast.c index 102a0f2..faae670 100644 --- a/src/screencast/pipewire_screencast.c +++ b/src/screencast/pipewire_screencast.c @@ -179,9 +179,40 @@ static void build_formats(struct spa_pod_builder *builder, struct xdpw_screencas } } - uint32_t *format; - wl_array_for_each(format, &cast->current_constraints.shm_formats) { - enum spa_video_format pw_format = xdpw_format_pw_from_drm_fourcc(*format); + struct xdpw_shm_format *shm_fmt; + wl_array_for_each(shm_fmt, &cast->current_constraints.shm_formats) { + enum spa_video_format pw_format = xdpw_format_pw_from_drm_fourcc(shm_fmt->fourcc); + if (pw_format != SPA_VIDEO_FORMAT_UNKNOWN) { + add_pod(params, build_format(builder, pw_format, + cast->current_constraints.width, cast->current_constraints.height, + cast->framerate, NULL, 0)); + } + } + + uint32_t fallback_formats[] = { DRM_FORMAT_ARGB8888, DRM_FORMAT_XRGB8888 }; + for (size_t i = 0; i < sizeof(fallback_formats) / sizeof(fallback_formats[0]); i++) { + bool already_advertised = false; + wl_array_for_each(shm_fmt, &cast->current_constraints.shm_formats) { + if (shm_fmt->fourcc == fallback_formats[i]) { + already_advertised = true; + break; + } + } + if (already_advertised) { + continue; + } + bool in_dmabuf = false; + struct xdpw_format_modifier_pair *fm_pair; + wl_array_for_each(fm_pair, &cast->current_constraints.dmabuf_format_modifier_pairs) { + if (fm_pair->fourcc == fallback_formats[i]) { + in_dmabuf = true; + break; + } + } + if (!in_dmabuf) { + continue; + } + enum spa_video_format pw_format = xdpw_format_pw_from_drm_fourcc(fallback_formats[i]); if (pw_format != SPA_VIDEO_FORMAT_UNKNOWN) { add_pod(params, build_format(builder, pw_format, cast->current_constraints.width, cast->current_constraints.height, diff --git a/src/screencast/screencast_common.c b/src/screencast/screencast_common.c index 721da03..86f6949 100644 --- a/src/screencast/screencast_common.c +++ b/src/screencast/screencast_common.c @@ -120,22 +120,27 @@ struct xdpw_buffer *xdpw_buffer_create(struct xdpw_screencast_instance *cast, case WL_SHM:; struct xdpw_shm_format *fmt; bool found = false; + uint32_t shm_stride; wl_array_for_each(fmt, &cast->current_constraints.shm_formats) { if (fmt->fourcc == format) { found = true; + shm_stride = fmt->stride; break; } } if (!found) { - logprint(ERROR, "xdpw: unable to find format: %d", format); - xdpw_buffer_destroy(buffer); - return NULL; - + int bpp = xdpw_bpp_from_drm_fourcc(format); + if (bpp <= 0) { + logprint(ERROR, "xdpw: unable to find format: %d", format); + xdpw_buffer_destroy(buffer); + return NULL; + } + shm_stride = bpp * buffer->width; } buffer->plane_count = 1; - buffer->size[0] = fmt->stride * buffer->height; - buffer->stride[0] = fmt->stride; + buffer->size[0] = shm_stride * buffer->height; + buffer->stride[0] = shm_stride; buffer->offset[0] = 0; buffer->fd[0] = anonymous_shm_open(); if (buffer->fd[0] == -1) { @@ -151,7 +156,7 @@ struct xdpw_buffer *xdpw_buffer_create(struct xdpw_screencast_instance *cast, } buffer->buffer = import_wl_shm_buffer(cast, buffer->fd[0], xdpw_format_wl_shm_from_drm_fourcc(format), - buffer->width, buffer->height, fmt->stride); + buffer->width, buffer->height, shm_stride); if (buffer->buffer == NULL) { logprint(ERROR, "xdpw: unable to create wl_buffer"); close(buffer->fd[0]); -- 2.54.0