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Aleksander HelgakerandDylan M. Taylor
7e40e12989
* craft-audio: ALAC decoder and encoder, ported from Apple's reference Add `craft_audio::alac`, a Rust port of Apple's ALAC reference implementation (macosforge/alac@c38887c, Apache-2.0): - `alac::Decoder`: packets to planar i32, bit depths 1-32, 1-8 channels, cookies in MP4/Matroska (24-byte config), CAF and old QuickTime form. Hostile input returns errors; arithmetic wraps where C would overflow. - `alac::Encoder`: 16/20/24/32 bits, 1-8 channels, fast mode, any frame length; same packets as the reference for the same input. - `SpecificConfig` (cookie parse/write), `wav_order`/`alac_order`, `channel_mask`. - Features `alac-decode` (in `decode-native`) and `alac-encode` (in `encode`). `TrackDecoder` decodes ALAC natively, so ALAC in MP4 and Matroska no longer goes through symphonia (CAF still does). Apple's reference writes the cookie's channel layout tag in host byte order; this writes it big-endian as its cookie description specifies and reads either. Tests: unit tests for each part, an MP4 decode-and-seek test without symphonia, and ffmpeg oracles both ways (bit-exact, 1-8 channels). NOTICE and each file's header record the Apache-2.0 origin. * craft-audio: ALAC review fixes (#731) - Decode the full-width residual escape 0xffffffff as i32::MIN; the reference's `nd + 1` wraps it to 0. - Require a whole element tag after the last channel (the end tag, after any fill or data stream elements), so a packet that lost its last byte is an error instead of decoding without damage. Other elements there end the packet, as in the reference. - Refuse an ALAC track with no sample rate in its cookie or container. - Conceal a damaged packet with the length its header gives (`alac::Decoder::packet_frames`), falling back to the last packet's. - Matroska: place ALAC packet starts at multiples of the frame length instead of the rounded block timestamps, so seeks land on the exact frame. MP4 keeps its exact sample-table timing. * craft-audio: exact Matroska ALAC seeks after a short packet (#731) Packet starts were multiples of the frame length, so a short packet before the end moved every later packet and seeks after it returned the wrong frames. When a packet's timestamp is further from that multiple than its rounding allows, the starts are now counted from the earlier packets' headers (read once and kept). Other codecs with a fixed packet length fall back to the timestamp, as before. --------- Co-authored-by: Dylan M. Taylor <dylan@dylanmtaylor.com>