fix: HEVC frame delimiter detection — NAL type extraction was wrong

dami etoile committed Jun 24cc543a9

HEVC NAL types are encoded as (byte >> 1) & 0x3f, not byte & 0x7f.
The old code checked (byte & 0x7f) == 35, which never matched because
HEVC AUD (type 35) appears as byte 0x46 (35 << 1 = 70 = 0x46).

This is why H.265 produced zero frames — the delimiter finder never
found a frame boundary, so no frames were ever emitted to the client.

H.264 was unaffected because its NAL type mask (byte & 0x1f) happened
to work for type 9 values.

commit: cc543a92226ac53ed945950552c2661a50e28e5b
parent: a69055418c4455959a6abd253d15dea95bdd60ce
author: dami etoile <dami.etoile@gmail.com>

1 file changed, +20 -11wrap lines

src-tauri/src/commands.rs

+++++++++++++++++++-----------

M src-tauri/src/commands.rs +20 -11

@@ -870,26 +870,29 @@ fn codec_format(codec: &str) -> (&'static str, &'static str) {
870870 }871871 872872 /// Find the next frame delimiter in the NAL stream.873-/// H.264/H.265: AUD start code (00 00 00 01 + NAL type 9 for H.264, type 35 for H.265)873+/// H.264/H.265: AUD start code (NAL type 9 for H.264, type 35 for H.265)874874 /// AV1: temporal delimiter OBU875875 fn find_next_frame_delim(data: &[u8], from: usize, codec: &str) -> Option<usize> {876-    let aud_nal_type = match codec {877-        "h265" => 35, // HEVC AUD878-        _ => 9,       // H.264 AUD879-    };880-881876     let mut i = from;882877     while i + 4 < data.len() {883878         if data[i] == 0 && data[i + 1] == 0 {884879             if data[i + 2] == 0 && i + 3 < data.len() && data[i + 3] == 1 {885880                 // 4-byte start code886881                 if codec == "av1" {887-                    // AV1 temporal delimiter: OBU type 2 (0x12 or 0x22 with extension flag)882+                    // AV1 temporal delimiter: OBU type 2 (0x10 in type field)888883                     if i + 4 < data.len() && (data[i + 4] & 0x38) == 0x10 {889884                         return Some(i);890885                     }891-                } else if i + 4 < data.len() && (data[i + 4] & 0x7f) == aud_nal_type {892-                    return Some(i);886+                } else if codec == "h265" {887+                    // HEVC NAL type is (byte >> 1) & 0x3f, AUD = 35888+                    if i + 4 < data.len() && ((data[i + 4] >> 1) & 0x3f) == 35 {889+                        return Some(i);890+                    }891+                } else {892+                    // H.264 NAL type is byte & 0x1f, AUD = 9893+                    if i + 4 < data.len() && (data[i + 4] & 0x1f) == 9 {894+                        return Some(i);895+                    }893896                 }894897                 i += 4;895898                 continue;@@ -900,8 +903,14 @@ fn find_next_frame_delim(data: &[u8], from: usize, codec: &str) -> Option<usize>
900903                     if i + 3 < data.len() && (data[i + 3] & 0x38) == 0x10 {901904                         return Some(i);902905                     }903-                } else if i + 3 < data.len() && (data[i + 3] & 0x7f) == aud_nal_type {904-                    return Some(i);906+                } else if codec == "h265" {907+                    if i + 3 < data.len() && ((data[i + 3] >> 1) & 0x3f) == 35 {908+                        return Some(i);909+                    }910+                } else {911+                    if i + 3 < data.len() && (data[i + 3] & 0x1f) == 9 {912+                        return Some(i);913+                    }905914                 }906915                 i += 3;907916                 continue;