audio: ffmpeg_dec: add ALAC decoder and FLAC/ALAC encoder support by lgirdwood · Pull Request #11427 · thesofproject/sof

lgirdwood · 2026-11-09T21:49:20Z

Add Phase 1 lossless compress playback and capture codecs to ffmpeg_dec using native fixed-point libavcodec implementations:

ALAC decoder (CONFIG_FFMPEG_DEC_ALAC, SND_AUDIOCODEC_ALAC):
- Apple .caf container parser (kuki chunk 36-byte ALAC magic cookie extraction and data chunk framing) and inline 36-byte QuickTime 'alac' atom header support.
- Self-delimiting unparsed frame consumption tracking via GetBitContext and partial-frame reassembly across LL period boundaries.
FLAC encoder (CONFIG_FFMPEG_ENC_FLAC, SND_AUDIOCODEC_FLAC):
- Native libavcodec flac encoder configured with fixed integer LPC predictors (FF_LPC_TYPE_FIXED, compression_level = 1) for deterministic low-MCPS DSP encoding.
- Prepends the 42-byte "fLaC" + STREAMINFO metadata block from avctx->extradata to produce a self-contained .flac stream.
- Bounds FlacEncodeContext dimensions on a build-tree copy of flacenc.c (FLAC_MAX_BLOCKSIZE=1152, rc_sums[1], FLAC_MAX_CHANNELS=2), reducing context allocation 122x from 7.35 MiB to 43.5 KiB.
ALAC encoder (CONFIG_FFMPEG_ENC_ALAC, SND_AUDIOCODEC_ALAC):
- Native libavcodec alac encoder configured with fixed LPC prediction (compression_level = 1) and planar S16 input conversion.
- Prepends the 36-byte QuickTime 'alac' magic cookie from avctx->extradata.
Topologies & Base FW Capabilities:
- Advertise SND_AUDIOCODEC_ALAC playback and SND_AUDIOCODEC_FLAC / SND_AUDIOCODEC_ALAC capture in IPC4_SOF_CODEC_INFO.
- Add sof-hda-generic-ffmpeg-alac-compr, sof-hda-generic-ffmpeg-flac-enc-compr, and sof-hda-generic-ffmpeg-alac-enc-compr development topology targets.

Hardware Verification (Aphid PTL ACE 3.0 & Spider TGL CAVS 2.5)

Verified end-to-end on both Aphid (ptl) and Spider (tgl):

ALAC .caf playback (comprC0D50, codec_id=15)
FLAC capture encode (comprC0D51, codec_id=10) + round-trip playback (comprC0D50)
ALAC capture encode (comprC0D51, codec_id=15) + round-trip playback (comprC0D50)

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9 open issues

The sed rule s/FLAC_MAX_BLOCKSIZE/1152/g replaces the macro name everywhere, which can break… · New
cd->in_buf is used for header sniffing (memcmp / alac_read_be32) without first… · New
When prev_len == 0, the code passes in directly to libavcodec (pkt_data = in) without… · New
ffmpeg_dec_pcm_to_frame() return value is ignored here as well. Please handle conversion failures… · New
ffmpeg_dec_pcm_to_frame() returns an error code, but the result is ignored. If it fails (e.g.,… · New
This relies on the internal layout of libavcodec's private ALACContext (priv_data) to read… · New
This relies on the internal layout of libavcodec's private ALACContext (priv_data) to read… · New
av_log_set_level() changes a global libav* logging level, which can affect other decoder/encoder… · New
These comments say encode is provided via ffmpeg_dec, but the encode path is implemented under… · New

_{Review effort: Lite}

Update get_codec_info() comments for FLAC, ALAC, SBC/mSBC, G.722, and aptX compress capture entries to reference ffmpeg_enc instead of ffmpeg_dec. Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

Consolidate sample-format conversion to Q1.31 using sign_extend_s24(), Q_SHIFT(), and Q_CONVERT_QTOD() via sof_pcm_sample_to_q31(), and remove the duplicate S24/S32-to-S16 conversion helpers from ffmpeg-encode.c. Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

- Add configure_avctx() and is_trailing_eof() hooks to struct ffmpeg_dec_codec_ops and move G.722/aptX configuration out of core ffmpeg_dec-ffmpeg.c. - Always stage unparsed payloads into ff->pktbuf and zero-pad AV_INPUT_BUFFER_PADDING_SIZE even when prev_len == 0. - Preserve and restore av_log_get_level() across unparsed frame decode calls. Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

Copilot

🟡 Changes recommended

The unconditional eight-byte peek stalls valid six-byte raw ALAC frames, preventing decoding and end-of-stream completion; eight bytes should be required only for possible CAF headers or inline ALAC atoms.

1 open issue

Avoid requiring eight bytes before decoding short valid ALAC streams · New

9 resolved since last review

When prev_len == 0, the code passes in directly to libavcodec (pkt_data = in) without…
cd->in_buf is used for header sniffing (memcmp / alac_read_be32) without first…
The sed rule s/FLAC_MAX_BLOCKSIZE/1152/g replaces the macro name everywhere, which can break…
av_log_set_level() changes a global libav* logging level, which can affect other decoder/encoder…
This relies on the internal layout of libavcodec's private ALACContext (priv_data) to read…
This relies on the internal layout of libavcodec's private ALACContext (priv_data) to read…
ffmpeg_dec_pcm_to_frame() returns an error code, but the result is ignored. If it fails (e.g.,…
ffmpeg_dec_pcm_to_frame() return value is ignored here as well. Please handle conversion failures…
These comments say encode is provided via ffmpeg_dec, but the encode path is implemented under…

_{Review effort: Balanced}

- Peek ALAC_HEADER_TAG_SIZE (4 bytes) first into cd->in_buf, requiring 8 bytes only for CAF/'alac' header detection. - Replace container/cookie magic numbers with named ALAC_* defines. - Pin libavcodec version (61.19.101) with _Static_assert and validate gb_buffer/gb_buffer_end bounds in ffmpeg_dec_alac_frame_bytes_consumed(). - Implement configure_avctx() and is_trailing_eof() hooks for ALAC. Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

- Restrict FLAC_MAX_BLOCKSIZE sed substitutions in ffmpeg.cmake so the #define FLAC_MAX_BLOCKSIZE identifier is not overwritten. - Check ffmpeg_dec_pcm_to_frame() return values and propagate errors in the FLAC, ALAC, SBC, G.722, and aptX encoders. Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

intel-sofci · 2026-11-14T21:17:38Z

PR 11427: test results

Run date: 2026-11-14 20:57 UTC

Tested commit: 53219497139d1215adbc8bc3e84e692092eaabbe

lgirdwood · 2026-11-15T15:30:52Z

CI failure unrelated.

lgirdwood mentioned this pull request Nov 10, 2026

ffmpeg_dec: add Bluetooth SBC/mSBC, G.722, and aptX decode and encode support #11431

Merged

lgirdwood force-pushed the topic/ffmpeg-lossless branch 2 times, most recently from 2a735e9 to e3da217 Compare November 11, 2026 00:00

lgirdwood requested a balanced review from Copilot November 11, 2026 20:27

Copilot AI reviewed Nov 11, 2026

lgirdwood requested a balanced review from Copilot November 13, 2026 17:41

Copilot AI reviewed Nov 13, 2026

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lgirdwood commented Nov 14, 2026

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Comment thread src/audio/ffmpeg_dec/ffmpeg_dec-convert.c Resolved

Comment thread src/audio/ffmpeg_dec/ffmpeg_dec-ffmpeg.c Resolved

Comment thread src/audio/ffmpeg_dec/ffmpeg_dec-alac.c Resolved

lrgirdwo added 3 commits November 14, 2026 17:10

audio: base_fw: fix ffmpeg_enc comments in codec capability list

2ccf73a

Update get_codec_info() comments for FLAC, ALAC, SBC/mSBC, G.722, and aptX compress capture entries to reference ffmpeg_enc instead of ffmpeg_dec. Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

lgirdwood force-pushed the topic/ffmpeg-lossless branch from e3da217 to 10764ee Compare November 14, 2026 17:17

lgirdwood requested a balanced review from Copilot November 14, 2026 17:50

Copilot started reviewing on behalf of lgirdwood November 14, 2026 17:51

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Comment thread src/audio/ffmpeg_dec/ffmpeg_dec-alac.c Resolved

lrgirdwo added 2 commits November 14, 2026 19:05

lgirdwood force-pushed the topic/ffmpeg-lossless branch from 10764ee to 5321949 Compare November 14, 2026 19:09

lgirdwood marked this pull request as ready for review November 14, 2026 19:48

lgirdwood requested review from dbaluta, kv2019i, lbetlej, mmaka1 and plbossart as code owners November 14, 2026 19:48

lgirdwood merged commit 827dc01 into thesofproject:main Nov 15, 2026
44 of 45 checks passed

lgirdwood deleted the topic/ffmpeg-lossless branch November 15, 2026 15:31

lgirdwood mentioned this pull request Nov 15, 2026

audio: ffmpeg_dec: add aptX HD, ITU-T G.726, and ITU-T G.711 codecs #11462

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audio: ffmpeg_dec: add ALAC decoder and FLAC/ALAC encoder support - #11427

audio: ffmpeg_dec: add ALAC decoder and FLAC/ALAC encoder support#11427
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lgirdwood commented Nov 9, 2026

Hardware Verification (Aphid PTL ACE 3.0 & Spider TGL CAVS 2.5)

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🟡 Changes recommended

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intel-sofci commented Nov 14, 2026

PR 11427: test results

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lgirdwood commented Nov 15, 2026

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