[FFmpeg-devel] [PATCH] avcodec/liblc3{dec,enc}: Simplify sample_size, is_planar check, sample fmt selection (PR #20998)

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

PR #20998 opened by mkver
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20998
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20998.patch


>From e528d76b28240e5502fdea12ad9bf0a583420043 Mon Sep 17 00:00:00 2001
From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Date: Sat, 22 Nov 2025 23:56:14 +0100
Subject: [PATCH 1/2] avcodec/liblc3{dec,enc}: Simplify sample_size, is_planar
 check

Sample size is always sizeof(float), is planar is a simple if
given that these codecs only support float and planar float.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
 libavcodec/liblc3dec.c |  9 +++------
 libavcodec/liblc3enc.c | 15 ++++++---------
 2 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/libavcodec/liblc3dec.c b/libavcodec/liblc3dec.c
index 293325ba2b..a0989c88b0 100644
--- a/libavcodec/liblc3dec.c
+++ b/libavcodec/liblc3dec.c
@@ -123,8 +123,6 @@ static int liblc3_decode(AVCodecContext *avctx, AVFrame *frame,
     int channels = avctx->ch_layout.nb_channels;
     uint8_t *in = avpkt->data;
     int block_bytes, ret;
-    size_t sample_size;
-    int is_planar;
 
     frame->nb_samples = av_rescale(
         liblc3->frame_us, liblc3->srate_hz, 1000*1000);
@@ -132,13 +130,12 @@ static int liblc3_decode(AVCodecContext *avctx, AVFrame *frame,
         return ret;
 
     block_bytes = avpkt->size;
-    is_planar = av_sample_fmt_is_planar(avctx->sample_fmt);
-    sample_size = av_get_bytes_per_sample(avctx->sample_fmt);
+    int is_planar = avctx->sample_fmt == AV_SAMPLE_FMT_FLTP;
 
     for (int ch = 0; ch < channels; ch++) {
         int nbytes = block_bytes / channels + (ch < block_bytes % channels);
-        void *pcm_data = is_planar ? frame->extended_data[ch] :
-                                frame->extended_data[0] + ch * sample_size;
+        float *pcm_data = is_planar ? (float*)frame->extended_data[ch] :
+                                      (float*)frame->extended_data[0] + ch;
         int stride = is_planar ? 1 : channels;
 
         ret = lc3_decode(liblc3->decoder[ch], in, nbytes,
diff --git a/libavcodec/liblc3enc.c b/libavcodec/liblc3enc.c
index 8bdf6bd5d8..e64963b457 100644
--- a/libavcodec/liblc3enc.c
+++ b/libavcodec/liblc3enc.c
@@ -138,13 +138,8 @@ static int liblc3_encode(AVCodecContext *avctx, AVPacket *pkt,
     int block_bytes = liblc3->block_bytes;
     int channels = avctx->ch_layout.nb_channels;
     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);
-
     if ((ret = ff_get_encode_buffer(avctx, pkt, block_bytes, 0)) < 0)
         return ret;
 
@@ -158,14 +153,16 @@ static int liblc3_encode(AVCodecContext *avctx, AVPacket *pkt,
         liblc3->remaining_samples = 0;
     }
 
+    int is_planar = avctx->sample_fmt == AV_SAMPLE_FMT_FLTP;
+
     data_ptr = pkt->data;
     for (int ch = 0; ch < channels; ch++) {
         int nbytes = block_bytes / channels + (ch < block_bytes % channels);
 
-        const void *pcm = frame ?
-                    (is_planar ? frame->data[ch] :
-                    frame->data[0] + ch * sample_size) :
-                    (const void *)(const float[]){ 0 };
+        const float *pcm = frame ?
+                    (is_planar ? (const float*)frame->data[ch] :
+                    (const float*)frame->data[0] + ch) :
+                    (const float[]){ 0 };
 
         int stride = frame ? (is_planar ? 1 : channels) : 0;
 
-- 
2.49.1


>From b667579ab0cc96c679277f404d83ba682b59c180 Mon Sep 17 00:00:00 2001
From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Date: Sun, 23 Nov 2025 00:26:07 +0100
Subject: [PATCH 2/2] avcodec/liblc3dec: Simplify sample fmt selection

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
 libavcodec/liblc3dec.c | 19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

diff --git a/libavcodec/liblc3dec.c b/libavcodec/liblc3dec.c
index a0989c88b0..953445ecfa 100644
--- a/libavcodec/liblc3dec.c
+++ b/libavcodec/liblc3dec.c
@@ -43,14 +43,6 @@ static av_cold int liblc3_decode_init(AVCodecContext *avctx)
     int ep_mode;
     unsigned decoder_size;
 
-    static const struct {
-        enum AVSampleFormat av_format;
-        enum lc3_pcm_format lc3_format;
-    } format_map[] = {
-        { AV_SAMPLE_FMT_FLT,  LC3_PCM_FORMAT_FLOAT },
-        { AV_SAMPLE_FMT_FLTP, LC3_PCM_FORMAT_FLOAT },
-    };
-
     if (avctx->extradata_size < 6)
         return AVERROR_INVALIDDATA;
     if (channels < 0 || channels > DECODER_MAX_CHANNELS) {
@@ -90,15 +82,8 @@ 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) {
-        for (int i = 0; i < FF_ARRAY_ELEMS(format_map); i++) {
-            if (format_map[i].av_format == avctx->request_sample_fmt) {
-                avctx->sample_fmt = avctx->request_sample_fmt;
-                break;
-            }
-        }
-    }
+    avctx->sample_fmt = avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT ?
+                            AV_SAMPLE_FMT_FLT : AV_SAMPLE_FMT_FLTP;
 
     avctx->delay = lc3_hr_delay_samples(
         liblc3->hr_mode, liblc3->frame_us, liblc3->srate_hz);
-- 
2.49.1

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