[FFmpeg-devel] [PATCH] avcodec/liblc3: add support for multiple sample formats. (PR #20601)

[cenzhanquan1 via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

PR #20601 opened by cenzhanquan1
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20601
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20601.patch

- Decoder:
  - Respect request_sample_fmt if set, default to S16 instead of FLTP
  - Add support for S16, S16P, FLT and FLTP sample formats
  - Properly handle both planar and interleaved layouts
  - Calculate correct data pointers and stride for liblc3

- Encoder:
  - Add support for S16, S16P, FLT and FLTP sample formats
  - Remove hardcoded use of LC3_PCM_FORMAT_FLOAT
  - Handle both planar and interleaved input data
  - Update zero frame allocation to account for sample size

- Update codec capabilities to include all supported sample formats
- Enhance error handling for unsupported formats

Signed-off-by: cenzhanquan1 <cenzhanquan1@xiaomi.com>


>From 0e560e67ae62ba568b0bcf2dc10fb322cd8fff3f Mon Sep 17 00:00:00 2001
From: cenzhanquan1 <cenzhanquan1@xiaomi.com>
Date: Wed, 24 Sep 2025 22:43:18 +0800
Subject: [PATCH] avcodec/liblc3: add support for multiple sample formats.

- Decoder:
  - Respect request_sample_fmt if set, default to S16 instead of FLTP
  - Add support for S16, S16P, FLT and FLTP sample formats
  - Properly handle both planar and interleaved layouts
  - Calculate correct data pointers and stride for liblc3

- Encoder:
  - Add support for S16, S16P, FLT and FLTP sample formats
  - Remove hardcoded use of LC3_PCM_FORMAT_FLOAT
  - Handle both planar and interleaved input data
  - Update zero frame allocation to account for sample size

- Update codec capabilities to include all supported sample formats
- Enhance error handling for unsupported formats

Signed-off-by: cenzhanquan1 <cenzhanquan1@xiaomi.com>
---
 libavcodec/liblc3dec.c | 47 ++++++++++++++++++++++++++++++++++++------
 libavcodec/liblc3enc.c | 46 ++++++++++++++++++++++++++++++++++-------
 2 files changed, 79 insertions(+), 14 deletions(-)

diff --git a/libavcodec/liblc3dec.c b/libavcodec/liblc3dec.c
index d250ace38a..50154b911b 100644
--- a/libavcodec/liblc3dec.c
+++ b/libavcodec/liblc3dec.c
@@ -82,7 +82,12 @@ static av_cold int liblc3_decode_init(AVCodecContext *avctx)
             (char *)liblc3->decoder_mem + ch * decoder_size);
     }
 
-    avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;
+    if (avctx->request_sample_fmt != AV_SAMPLE_FMT_NONE) {
+        avctx->sample_fmt = avctx->request_sample_fmt;
+    } else {
+        avctx->sample_fmt = AV_SAMPLE_FMT_S16;
+    }
+
     avctx->delay = lc3_hr_delay_samples(
         liblc3->hr_mode, liblc3->frame_us, liblc3->srate_hz);
     avctx->internal->skip_samples = avctx->delay;
@@ -104,8 +109,10 @@ static int liblc3_decode(AVCodecContext *avctx, AVFrame *frame,
 {
     LibLC3DecContext *liblc3 = avctx->priv_data;
     int channels = avctx->ch_layout.nb_channels;
-    uint8_t *in = avpkt->data;
+    enum lc3_pcm_format liblc3_format;
     int block_bytes, ret;
+    size_t sample_size;
+    int is_planar;
 
     frame->nb_samples = av_rescale(
         liblc3->frame_us, liblc3->srate_hz, 1000*1000);
@@ -113,15 +120,43 @@ static int liblc3_decode(AVCodecContext *avctx, AVFrame *frame,
         return ret;
 
     block_bytes = avpkt->size;
+
+    switch (avctx->sample_fmt) {
+        case AV_SAMPLE_FMT_S16:
+        case AV_SAMPLE_FMT_S16P:
+            liblc3_format = LC3_PCM_FORMAT_S16;
+            break;
+        case AV_SAMPLE_FMT_FLT:
+        case AV_SAMPLE_FMT_FLTP:
+            liblc3_format = LC3_PCM_FORMAT_FLOAT;
+            break;
+        default:
+            av_log(NULL, AV_LOG_ERROR,
+                "Unsupported sample format %s\n",
+                av_get_sample_fmt_name(avctx->sample_fmt));
+            return AVERROR(EINVAL);
+    }
+
+    is_planar = av_sample_fmt_is_planar(avctx->sample_fmt);
+    sample_size = av_get_bytes_per_sample(avctx->sample_fmt);
+
     for (int ch = 0; ch < channels; ch++) {
         int nbytes = block_bytes / channels + (ch < block_bytes % channels);
+        void *pcm_data;
+        int stride;
 
-        ret = lc3_decode(liblc3->decoder[ch], in, nbytes,
-                         LC3_PCM_FORMAT_FLOAT, frame->data[ch], 1);
+        if (is_planar) {
+            pcm_data = frame->extended_data[ch];
+            stride = 1;
+        } else {
+            pcm_data = (uint8_t *)frame->extended_data[0] + ch * sample_size;
+            stride = channels;
+        }
+
+        ret = lc3_decode(liblc3->decoder[ch], avpkt->data + ch * nbytes, nbytes,
+                         liblc3_format, pcm_data, stride);
         if (ret < 0)
             return AVERROR_INVALIDDATA;
-
-        in += nbytes;
     }
 
     frame->nb_samples = FFMIN(frame->nb_samples, avpkt->duration);
diff --git a/libavcodec/liblc3enc.c b/libavcodec/liblc3enc.c
index 66007a90f3..8aee9304b9 100644
--- a/libavcodec/liblc3enc.c
+++ b/libavcodec/liblc3enc.c
@@ -137,10 +137,30 @@ static int liblc3_encode(AVCodecContext *avctx, AVPacket *pkt,
     LibLC3EncContext *liblc3 = avctx->priv_data;
     int block_bytes = liblc3->block_bytes;
     int channels = avctx->ch_layout.nb_channels;
+    enum lc3_pcm_format lc3_format;
     void *zero_frame = NULL;
-    uint8_t *data_ptr;
+    size_t sample_size;
+    int is_planar;
     int ret;
 
+    is_planar = av_sample_fmt_is_planar(avctx->sample_fmt);
+    sample_size = av_get_bytes_per_sample(avctx->sample_fmt);
+
+    switch (avctx->sample_fmt) {
+        case AV_SAMPLE_FMT_S16P:
+        case AV_SAMPLE_FMT_S16:
+            lc3_format = LC3_PCM_FORMAT_S16;
+            break;
+        case AV_SAMPLE_FMT_FLT:
+        case AV_SAMPLE_FMT_FLTP:
+            lc3_format = LC3_PCM_FORMAT_FLOAT;
+            break;
+        default:
+            av_log(avctx, AV_LOG_ERROR, "Unsupported sample format: %s\n",
+                    av_get_sample_fmt_name(avctx->sample_fmt));
+            return AVERROR(EINVAL);
+    }
+
     if ((ret = ff_get_encode_buffer(avctx, pkt, block_bytes, 0)) < 0)
         return ret;
 
@@ -152,20 +172,30 @@ static int liblc3_encode(AVCodecContext *avctx, AVPacket *pkt,
             return 0;
 
         liblc3->remaining_samples = 0;
-        zero_frame = av_mallocz(avctx->frame_size * sizeof(float));
+        zero_frame = av_mallocz(avctx->frame_size * channels * sample_size);
         if (!zero_frame)
             return AVERROR(ENOMEM);
     }
 
-    data_ptr = pkt->data;
     for (int ch = 0; ch < channels; ch++) {
-        const float *pcm = zero_frame ? zero_frame : frame->data[ch];
         int nbytes = block_bytes / channels + (ch < block_bytes % channels);
+        const void *pcm;
+        int stride;
+
+        if (zero_frame) {
+            pcm = (uint8_t *)zero_frame + ch * (is_planar ? avctx->frame_size * sample_size : sample_size);
+        } else {
+            if (is_planar) {
+                pcm = frame->data[ch];
+                stride = 1;
+            } else {
+                pcm = frame->data[0] + ch * sample_size;
+                stride = channels;
+            }
+        }
 
         lc3_encode(liblc3->encoder[ch],
-                   LC3_PCM_FORMAT_FLOAT, pcm, 1, nbytes, data_ptr);
-
-        data_ptr += nbytes;
+                   lc3_format, pcm, stride, nbytes, pkt->data + ch * nbytes);
     }
 
     if (zero_frame)
@@ -204,7 +234,7 @@ const FFCodec ff_liblc3_encoder = {
     .p.priv_class   = &class,
     .p.wrapper_name = "liblc3",
     CODEC_SAMPLERATES(96000, 48000, 32000, 24000, 16000, 8000),
-    CODEC_SAMPLEFMTS(AV_SAMPLE_FMT_FLTP),
+    CODEC_SAMPLEFMTS(AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_S16P),
     .priv_data_size = sizeof(LibLC3EncContext),
     .init           = liblc3_encode_init,
     .close          = liblc3_encode_close,
-- 
2.49.1

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