Re: [FFmpeg-devel] [PATCH] avformat: add Limitless Audio Format demuxer

[Paul B Mahol <onemda@gmail.com>]

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On 9/12/22, Paul B Mahol <onemda@gmail.com> wrote:
> Patch attached.
>

Updated patch attached.

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From 33efa252db96d9eac7f162f17b22c1cd8b3b1c14 Mon Sep 17 00:00:00 2001
From: Paul B Mahol <onemda@gmail.com>
Date: Sun, 11 Sep 2022 20:10:27 +0200
Subject: [PATCH] avformat: add LAF demuxer

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 libavformat/Makefile     |   1 +
 libavformat/allformats.c |   1 +
 libavformat/lafdec.c     | 271 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 273 insertions(+)
 create mode 100644 libavformat/lafdec.c

diff --git a/libavformat/Makefile b/libavformat/Makefile
index 5cdcda3239..19a4ba2a8f 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -319,6 +319,7 @@ OBJS-$(CONFIG_JV_DEMUXER)                += jvdec.o
 OBJS-$(CONFIG_KUX_DEMUXER)               += flvdec.o
 OBJS-$(CONFIG_KVAG_DEMUXER)              += kvag.o
 OBJS-$(CONFIG_KVAG_MUXER)                += kvag.o rawenc.o
+OBJS-$(CONFIG_LAF_DEMUXER)               += lafdec.o
 OBJS-$(CONFIG_LATM_MUXER)                += latmenc.o rawenc.o
 OBJS-$(CONFIG_LMLM4_DEMUXER)             += lmlm4.o
 OBJS-$(CONFIG_LOAS_DEMUXER)              += loasdec.o rawdec.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index cebd5e0c67..a545b5ff45 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -236,6 +236,7 @@ extern const AVInputFormat  ff_jv_demuxer;
 extern const AVInputFormat  ff_kux_demuxer;
 extern const AVInputFormat  ff_kvag_demuxer;
 extern const AVOutputFormat ff_kvag_muxer;
+extern const AVInputFormat  ff_laf_demuxer;
 extern const AVOutputFormat ff_latm_muxer;
 extern const AVInputFormat  ff_lmlm4_demuxer;
 extern const AVInputFormat  ff_loas_demuxer;
diff --git a/libavformat/lafdec.c b/libavformat/lafdec.c
new file mode 100644
index 0000000000..12b0d8540b
--- /dev/null
+++ b/libavformat/lafdec.c
@@ -0,0 +1,271 @@
+/*
+ * Limitless Audio Format demuxer
+ * Copyright (c) 2022 Paul B Mahol
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/intreadwrite.h"
+#include "avformat.h"
+#include "internal.h"
+
+#define MAX_STREAMS 4096
+
+typedef struct StreamParams {
+    AVChannelLayout layout;
+    float horizontal;
+    float vertical;
+    int lfe;
+    int stored;
+} StreamParams;
+
+typedef struct LAFContext {
+    uint8_t *data;
+    unsigned nb_stored;
+    unsigned stored_index;
+    unsigned index;
+    unsigned bpp;
+
+    StreamParams p[MAX_STREAMS];
+
+    int header_len;
+    uint8_t header[(MAX_STREAMS + 7) / 8];
+} LAFContext;
+
+static int laf_probe(const AVProbeData *p)
+{
+    if (memcmp(p->buf, "LIMITLESS", 9))
+        return 0;
+    if (memcmp(p->buf + 9, "HEAD", 4))
+        return 0;
+    return AVPROBE_SCORE_MAX;
+}
+
+static int laf_read_header(AVFormatContext *ctx)
+{
+    LAFContext *s = ctx->priv_data;
+    AVIOContext *pb = ctx->pb;
+    unsigned st_count, mode;
+    unsigned sample_rate;
+    int64_t duration;
+    int codec_id;
+    int quality;
+    int bpp;
+
+    avio_skip(pb, 9);
+    if (avio_rb32(pb) != MKBETAG('H','E','A','D'))
+        return AVERROR_INVALIDDATA;
+
+    quality = avio_r8(pb);
+    if (quality > 3)
+        return AVERROR_INVALIDDATA;
+    mode = avio_r8(pb);
+    if (mode > 1)
+        return AVERROR_INVALIDDATA;
+    st_count = avio_rl32(pb);
+    if (st_count == 0 || st_count > MAX_STREAMS)
+        return AVERROR_INVALIDDATA;
+
+    for (int i = 0; i < st_count; i++) {
+        StreamParams *stp = &s->p[i];
+
+        stp->vertical = av_int2float(avio_rl32(pb));
+        stp->horizontal = av_int2float(avio_rl32(pb));
+        stp->lfe = avio_r8(pb);
+        if (stp->lfe) {
+            stp->layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MASK(1, (AV_CH_LOW_FREQUENCY));
+        } else if (stp->vertical == 0.f &&
+                   stp->horizontal == 0.f) {
+            stp->layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MASK(1, (AV_CH_FRONT_CENTER));
+        } else if (stp->vertical == 0.f &&
+                   stp->horizontal == -30.f) {
+            stp->layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MASK(1, (AV_CH_FRONT_LEFT));
+        } else if (stp->vertical == 0.f &&
+                   stp->horizontal == 30.f) {
+            stp->layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MASK(1, (AV_CH_FRONT_RIGHT));
+        } else if (stp->vertical == 0.f &&
+                   stp->horizontal == -110.f) {
+            stp->layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MASK(1, (AV_CH_SIDE_LEFT));
+        } else if (stp->vertical == 0.f &&
+                   stp->horizontal == 110.f) {
+            stp->layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MASK(1, (AV_CH_SIDE_RIGHT));
+        } else {
+            stp->layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
+        }
+    }
+
+    sample_rate = avio_rl32(pb);
+    duration = avio_rl64(pb) / st_count;
+
+    switch (quality) {
+    case 0:
+        codec_id = AV_CODEC_ID_PCM_U8;
+        bpp = 1;
+        break;
+    case 1:
+        codec_id = AV_CODEC_ID_PCM_S16LE;
+        bpp = 2;
+        break;
+    case 2:
+        codec_id = AV_CODEC_ID_PCM_F32LE;
+        bpp = 4;
+        break;
+    case 3:
+        codec_id = AV_CODEC_ID_PCM_S24LE;
+        bpp = 3;
+        break;
+    }
+
+    s->index = 0;
+    s->stored_index = 0;
+    s->bpp = bpp;
+    if ((int64_t)bpp * st_count * (int64_t)sample_rate >= INT32_MAX)
+        return AVERROR_INVALIDDATA;
+    s->data = av_calloc(st_count * sample_rate, bpp);
+    if (!s->data)
+        return AVERROR(ENOMEM);
+
+    for (int st = 0; st < st_count; st++) {
+        StreamParams *stp = &s->p[st];
+        AVCodecParameters *par;
+        AVStream *st = avformat_new_stream(ctx, NULL);
+        if (!st)
+            return AVERROR(ENOMEM);
+
+        par = st->codecpar;
+        par->codec_id = codec_id;
+        par->codec_type = AVMEDIA_TYPE_AUDIO;
+        par->ch_layout.nb_channels = 1;
+        par->ch_layout = stp->layout;
+        par->sample_rate = sample_rate;
+        st->duration = duration;
+
+        avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
+    }
+
+    s->header_len = (ctx->nb_streams + 7) / 8;
+
+    return 0;
+}
+
+static int laf_read_packet(AVFormatContext *ctx, AVPacket *pkt)
+{
+    AVIOContext *pb = ctx->pb;
+    LAFContext *s = ctx->priv_data;
+    AVStream *st = ctx->streams[0];
+    const int bpp = s->bpp;
+    StreamParams *stp;
+    int64_t pos;
+    int ret;
+
+    pos = avio_tell(pb);
+
+again:
+    if (avio_feof(pb))
+        return AVERROR_EOF;
+
+    if (s->index >= ctx->nb_streams) {
+        int cur_st = 0, st_count = 0, st_index = 0;
+
+        avio_read(pb, s->header, s->header_len);
+        for (int i = 0; i < s->header_len; i++) {
+            uint8_t val = s->header[i];
+
+            for (int j = 0; j < 8 && cur_st < ctx->nb_streams; j++, cur_st++) {
+                StreamParams *stp = &s->p[st_index];
+
+                stp->stored = 0;
+                if (val & 1) {
+                    stp->stored = 1;
+                    st_count++;
+                }
+                val >>= 1;
+                st_index++;
+            }
+        }
+
+        s->index = s->stored_index = 0;
+        s->nb_stored = st_count;
+        if (!st_count)
+            return AVERROR_INVALIDDATA;
+        ret = avio_read(pb, s->data, st_count * st->codecpar->sample_rate * bpp);
+        if (ret < 0)
+            return ret;
+    }
+
+    st = ctx->streams[s->index];
+    stp = &s->p[s->index];
+    while (!stp->stored) {
+        s->index++;
+        if (s->index >= ctx->nb_streams)
+            goto again;
+        stp = &s->p[s->index];
+    }
+    st = ctx->streams[s->index];
+
+    ret = av_new_packet(pkt, st->codecpar->sample_rate * bpp);
+    if (ret < 0)
+        return ret;
+
+    switch (bpp) {
+    case 1:
+        for (int n = 0; n < st->codecpar->sample_rate; n++)
+            pkt->data[n] = s->data[n * s->nb_stored + s->stored_index];
+        break;
+    case 2:
+        for (int n = 0; n < st->codecpar->sample_rate; n++)
+            AV_WN16(pkt->data + n * 2, AV_RN16(s->data + n * s->nb_stored * 2 + s->stored_index * 2));
+        break;
+    case 3:
+        for (int n = 0; n < st->codecpar->sample_rate; n++)
+            AV_WL24(pkt->data + n * 3, AV_RL24(s->data + n * s->nb_stored * 3 + s->stored_index * 3));
+        break;
+    case 4:
+        for (int n = 0; n < st->codecpar->sample_rate; n++)
+            AV_WN32(pkt->data + n * 4, AV_RN32(s->data + n * s->nb_stored * 4 + s->stored_index * 4));
+        break;
+    }
+
+    pkt->stream_index = s->index;
+    pkt->pos = pos;
+    s->index++;
+    s->stored_index++;
+
+    return 0;
+}
+
+static int laf_read_seek(AVFormatContext *ctx, int stream_index,
+                         int64_t timestamp, int flags)
+{
+    LAFContext *s = ctx->priv_data;
+
+    s->stored_index = s->index = s->nb_stored = 0;
+
+    return -1;
+}
+
+const AVInputFormat ff_laf_demuxer = {
+    .name           = "laf",
+    .long_name      = NULL_IF_CONFIG_SMALL("LAF (Limitless Audio Format)"),
+    .priv_data_size = sizeof(LAFContext),
+    .read_probe     = laf_probe,
+    .read_header    = laf_read_header,
+    .read_packet    = laf_read_packet,
+    .read_seek      = laf_read_seek,
+    .extensions     = "laf",
+    .flags          = AVFMT_GENERIC_INDEX,
+};
-- 
2.37.2


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