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Merge pull request #118 from HEOJUNFO/fix/probe-pixfmt-from-config 

codecs: MP4/MOV pixel format and alpha come from hvcC, avcC and the ProRes frame header (#103)
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Brandon Thomas 2026-10-07 05:57:10 -04:00 committed by GitHub
parent 79057f9c36 f761a299a7
commit 36d8114d2f
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1 changed files with 122 additions and 8 deletions
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130
crates/codecs/src/mp4.rs
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@ -148,7 +148,7 @@ impl Mp4Source {
codec: codec_label(&entry.codec),
pixel_format: pixfmt_label(&entry.codec),
color,
has_alpha: matches!(&entry.codec, CodecConfig::ProRes { fourcc } if fourcc.0 == *b"ap4h" || fourcc.0 == *b"ap4x"),
has_alpha: false,
bitrate,
hdr: entry.video.as_ref().and_then(|v| hdr_metadata(v.mastering_display.as_ref(), v.content_light)),
};
@ -170,6 +170,19 @@ impl Mp4Source {
info.has_alpha = h.alpha;
}
}
if matches!(entry.codec, CodecConfig::ProRes { .. }) {
// a 4444 fourcc doesn't mean the frames carry alpha (alpha_channel_type does): read the first frame header
let s0 = &t.samples[0];
if let Some(h) = filmcraft_media::reader::read_range(&*bytes.0, s0.offset, s0.size as usize).ok().and_then(|d| filmcraft_prores::probe(&d).ok())
{
info.has_alpha = h.alpha != filmcraft_prores::AlphaType::None;
let sub = match h.chroma {
filmcraft_prores::ChromaFormat::Yuv422 => "4:2:2 10-bit",
filmcraft_prores::ChromaFormat::Yuv444 => "4:4:4 12-bit",
};
info.pixel_format = format!("{} {sub}", if info.has_alpha { "YUVA" } else { "YUV" });
}
}
info
});
let audio = atrack.map(|i| {
@ -445,14 +458,37 @@ fn codec_label(c: &CodecConfig) -> String {
}
}
/// "YUV 4:2:2 10-bit" from an H.264 / HEVC `chroma_format_idc` and bit depth.
fn yuv_label(chroma_format_idc: u32, bits: u32) -> String {
let sub = match chroma_format_idc {
0 => "4:0:0",
1 => "4:2:0",
2 => "4:2:2",
_ => "4:4:4",
};
format!("YUV {sub} {bits}-bit")
}
/// `chroma_format_idc` and luma bit depth of an H.264 track: from the `avcC` High-profile extension
/// (ISO/IEC 14496-15 §5.3.3), else from its first SPS. The profile alone can't say (High 4:2:2 is
/// 8 or 10-bit, High 10 can be 8-bit).
fn avc_format(a: &filmcraft_isobmff::AvcConfig) -> Option<(u32, u32)> {
// reserved bits set: '111111' chroma_format, '11111' bit_depth_luma_minus8 (else not an extension)
if !matches!(a.profile, 66 | 77 | 88)
&& let &[chroma, depth, ..] = a.ext.as_slice()
&& chroma & 0xFC == 0xFC
&& depth & 0xF8 == 0xF8
{
return Some(((chroma & 3) as u32, (depth & 7) as u32 + 8));
}
let sps = filmcraft_h264::params::Sps::parse(&filmcraft_bitstream::unescape_rbsp(a.sps.first()?.get(1..)?)).ok()?;
Some((sps.chroma_format_idc, sps.bit_depth_luma))
}
fn pixfmt_label(c: &CodecConfig) -> String {
match c {
CodecConfig::Avc(a) => match a.profile {
110 => "YUV 4:2:0 10-bit".into(),
122 => "YUV 4:2:2".into(),
244 => "YUV 4:4:4".into(),
_ => "YUV 4:2:0 8-bit".into(),
},
CodecConfig::Avc(a) => avc_format(a).map(|(chroma, bits)| yuv_label(chroma, bits)).unwrap_or_default(),
CodecConfig::Hevc(h) => yuv_label(h.chroma_format_idc as u32, h.bit_depth_luma as u32),
CodecConfig::Vp9(c) => {
let sub = match c.chroma_subsampling {
2 => "4:2:2",
@ -461,7 +497,8 @@ fn pixfmt_label(c: &CodecConfig) -> String {
};
format!("YUV {sub} {}-bit", c.bit_depth.max(8))
}
CodecConfig::ProRes { fourcc } if fourcc.0[2] == b'4' => "YUVA 4:4:4 12-bit".into(),
// 4444 until the first frame header says whether it codes alpha (`open_reader`)
CodecConfig::ProRes { fourcc } if fourcc.0[2] == b'4' => "YUV 4:4:4 12-bit".into(),
CodecConfig::ProRes { .. } => "YUV 4:2:2 10-bit".into(),
CodecConfig::Jpeg { .. } => "YUV 4:2:x 8-bit".into(),
_ => String::new(),
@ -653,4 +690,81 @@ mod tests {
let s = Mp4Source::open("cw2.mov", rotated_mov([0, 2 * ONE, 0, -2 * ONE, 0, 0, 64 * ONE, 0, W])).expect("open");
assert_eq!(s.info().video.as_ref().map(|v| (v.width, v.height)), Some((32, 64)));
}
#[test]
fn hevc_pixel_format_comes_from_hvcc() {
for (chroma, bits, want) in [(1, 8, "YUV 4:2:0 8-bit"), (1, 10, "YUV 4:2:0 10-bit"), (2, 8, "YUV 4:2:2 8-bit"), (2, 10, "YUV 4:2:2 10-bit")] {
let c = filmcraft_isobmff::HevcConfig { general_profile_idc: 1, chroma_format_idc: chroma, bit_depth_luma: bits, ..Default::default() };
assert_eq!(pixfmt_label(&CodecConfig::Hevc(c)), want);
}
}
/// A High-profile SPS NAL unit (ITU-T H.264 §7.3.2.1.1) with the given chroma format and bit depth, 16×16.
fn high_sps(profile: u8, chroma: u32, bits: u32) -> Vec<u8> {
let mut w = filmcraft_bitstream::BitWriter::new();
w.write_bits(0x67, 8);
w.write_bits(profile as u32, 8);
w.write_bits(0, 8); // constraint flags
w.write_bits(30, 8); // level
w.write_ue(0); // seq_parameter_set_id
w.write_ue(chroma);
if chroma == 3 {
w.write_bit(false); // separate_colour_plane_flag
}
w.write_ue(bits - 8); // luma
w.write_ue(bits - 8); // chroma
w.write_bits(0, 2); // no transform bypass, no scaling matrices
w.write_ue(0); // log2_max_frame_num_minus4
w.write_ue(2); // pic_order_cnt_type
w.write_ue(1); // max_num_ref_frames
w.write_bit(false); // gaps_in_frame_num_allowed
w.write_ue(0); // pic_width_in_mbs_minus1
w.write_ue(0); // pic_height_in_map_units_minus1
w.write_bits(0b110, 3); // frame_mbs_only, direct_8x8_inference, no cropping
w.write_bit(false); // no VUI
w.rbsp_trailing();
w.finish()
}
#[test]
fn avc_pixel_format_comes_from_avcc_not_the_profile() {
let avc =
|profile: u8, sps: Vec<u8>, ext: Vec<u8>| CodecConfig::Avc(filmcraft_isobmff::AvcConfig { profile, sps: vec![sps], ext, ..Default::default() });
// High 4:2:2 at 10 and 8 bits, from the avcC extension (chroma_format 2, bit_depth_luma_minus8)
assert_eq!(pixfmt_label(&avc(122, high_sps(122, 2, 10), vec![0xFE, 0xFA, 0xFA, 0])), "YUV 4:2:2 10-bit");
assert_eq!(pixfmt_label(&avc(122, high_sps(122, 2, 8), vec![0xFE, 0xF8, 0xF8, 0])), "YUV 4:2:2 8-bit");
// no extension (or not a valid one): the SPS says
assert_eq!(pixfmt_label(&avc(122, high_sps(122, 2, 10), Vec::new())), "YUV 4:2:2 10-bit");
assert_eq!(pixfmt_label(&avc(110, high_sps(110, 1, 10), vec![0, 0, 0, 0])), "YUV 4:2:0 10-bit");
assert_eq!(pixfmt_label(&avc(244, high_sps(244, 3, 10), Vec::new())), "YUV 4:4:4 10-bit");
// an unreadable SPS and no extension: unknown, not a guess
assert_eq!(pixfmt_label(&avc(122, vec![0x67, 122], Vec::new())), "");
}
/// A one-frame 32×16 ProRes MOV with the given profile, chroma format and fourcc.
fn prores_mov(profile: filmcraft_prores::Profile, fourcc: &[u8; 4], chroma: filmcraft_prores::ChromaFormat, alpha: bool) -> Arc<[u8]> {
let (w, h) = (32u32, 16u32);
let fr = filmcraft_prores::Frame::new(w, h, chroma, if chroma == filmcraft_prores::ChromaFormat::Yuv444 { 12 } else { 10 }, alpha);
let data = filmcraft_prores::Encoder::new(profile, w, h).encode(&fr).expect("encode");
let mut mux = Mp4Writer::new(std::io::Cursor::new(Vec::new()), WriterOptions::new(Brand::Mov)).expect("writer");
let t = mux.add_track(TrackConfig::new(SampleEntry::prores(FourCc(*fourcc), w as u16, h as u16), 25)).expect("track");
mux.write_sample(t, WriteSample { data: &data, duration: 1, composition_offset: 0, is_sync: true }).expect("sample");
mux.finish().expect("finish").into_inner().into()
}
/// `ap4h` / `ap4x` don't imply alpha: the frame header's alpha_channel_type does.
#[test]
fn prores_alpha_comes_from_the_frame_header() {
use filmcraft_prores::{ChromaFormat, Profile};
for (profile, fourcc, chroma, alpha, want) in [
(Profile::P4444, b"ap4h", ChromaFormat::Yuv444, false, "YUV 4:4:4 12-bit"),
(Profile::P4444, b"ap4h", ChromaFormat::Yuv444, true, "YUVA 4:4:4 12-bit"),
(Profile::P4444Xq, b"ap4x", ChromaFormat::Yuv444, false, "YUV 4:4:4 12-bit"),
(Profile::Hq, b"apch", ChromaFormat::Yuv422, false, "YUV 4:2:2 10-bit"),
] {
let s = Mp4Source::open("p.mov", prores_mov(profile, fourcc, chroma, alpha)).expect("open");
let v = s.info().video.as_ref().expect("video");
assert_eq!((v.pixel_format.as_str(), v.has_alpha), (want, alpha), "{}", String::from_utf8_lossy(fourcc));
}
}
}