Document parser scope and add CI

.github/workflows/test.yml

@@ -0,0 +1,19 @@
+name: Test
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v7
+      - uses: prantlf/setup-v-action@v4
+      - run: v test .

README.md

@@ -1,9 +1,55 @@
+# H.264 bitstream parser for V
 
+This module parses the H.264/AVC syntax needed by Vulkan Video applications:
+NAL headers, sequence and picture parameter sets (SPS/PPS), video usability
+information (VUI), and slice headers.
 
-# h264 Video Decoder
-Provides functions to decode h264 video data.
-See [ITU-T H.264 (08/2021)](https://www.itu.int/ITU-T/recommendations/rec.aspx?rec=14659) for details.
+It is **not** a video decoder: it does not perform entropy decoding, motion
+compensation, inverse transforms, or produce pixels. The
+[`v_vulkan_video`](https://github.com/antono2/v_vulkan_video) player uses these
+parsed structures to prepare hardware decode operations.
 
 ## Install
-`v install https://github.com/antono2/h264`
 
+```bash
+v install https://github.com/antono2/h264
+```
+
+## Minimal example
+
+```v
+import h264
+
+mut stream := h264.Bitstream{}
+stream.init([u8(0x67)]) // forbidden_zero_bit=0, nal_ref_idc=3, type=SPS
+
+mut header := h264.NetworkAbstractionLayerHeader{}
+header.read_nal_header(mut stream)
+assert header.type == .sequence_parameter_set
+```
+
+`Bitstream.init()` expects raw RBSP/NAL bytes in memory. Container extraction,
+length prefixes or Annex-B start codes, emulation-prevention removal, frame
+reordering, and decoded-picture management remain the caller's responsibility.
+
+## Safety and supported scope
+
+The parser exposes low-level syntax structures rather than a defensive media
+API. Some invalid syntax is rejected with assertions, while truncated fields
+can read as zero at end of input. Validate untrusted container lengths and NAL
+boundaries before parsing them.
+
+The implementation covers the syntax exercised by the Vulkan Video H.264
+player and is not yet a claim of complete support for every profile, extension,
+bit depth, chroma format, or interlaced stream.
+
+## Tests
+
+The included tests are software-only and require no GPU:
+
+```bash
+v test .
+```
+
+They cover RBSP look-ahead behavior and representative High-profile SPS/PPS
+parsing used by the player.

h264.v

@@ -884,7 +884,7 @@ pub fn (mut sh SliceHeader) read_slice_header(nal &NetworkAbstractionLayerHeader
 	}
 	sh.read_ref_pic_list_reordering(mut b)
 	if pps.weighted_pred_flag != 0
-		&& ((sh.is_slice_type(SH_SLICE_TYPE.p) || sh.is_slice_type(SH_SLICE_TYPE.sp))
+		&& (sh.is_slice_type(SH_SLICE_TYPE.p) || sh.is_slice_type(SH_SLICE_TYPE.sp)
 		|| (pps.weighted_bipred_idc == 1 && sh.is_slice_type(SH_SLICE_TYPE.b))) {
 		sh.read_pred_weight_table(sps, pps, mut b)
 	}

v.mod

@@ -1,11 +1,11 @@
 Module {
   name: 'h264'
   author: 'Anton Oreskin'
-  description: 'Decoder for the h264 video format'
+  description: 'Low-level H.264 bitstream and parameter-set parser'
   version: '1.0.0'
   repo_url: 'https://github.com/antono2/h264'
   vcs: 'git'
-  tags: ['V','h264','decoder']
+  tags: ['V','h264','parser','bitstream']
   license: 'MIT'
   dependencies: []
 }