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* [FFmpeg-devel] [PATCH] A-pac demuxer and decoder
@ 2022-09-21  7:23 Paul B Mahol
  2022-09-23 17:48 ` Paul B Mahol
  2022-09-23 18:31 ` James Almer
  0 siblings, 2 replies; 3+ messages in thread
From: Paul B Mahol @ 2022-09-21  7:23 UTC (permalink / raw)
  To: FFmpeg development discussions and patches

[-- Attachment #1: Type: text/plain, Size: 18 bytes --]

Patches attached.

[-- Attachment #2: 0001-avcodec-add-APAC-decoder.patch --]
[-- Type: text/x-patch, Size: 11219 bytes --]

From 751526c456d09bd22a6316196219d79876ae74f1 Mon Sep 17 00:00:00 2001
From: Paul B Mahol <onemda@gmail.com>
Date: Mon, 19 Sep 2022 22:14:05 +0200
Subject: [PATCH 1/2] avcodec: add APAC decoder

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 libavcodec/Makefile     |   1 +
 libavcodec/allcodecs.c  |   1 +
 libavcodec/apac.c       | 269 ++++++++++++++++++++++++++++++++++++++++
 libavcodec/codec_desc.c |   7 ++
 libavcodec/codec_id.h   |   1 +
 5 files changed, 279 insertions(+)
 create mode 100644 libavcodec/apac.c

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index c836252664..b9aa6efaac 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -214,6 +214,7 @@ OBJS-$(CONFIG_AMRWB_DECODER)           += amrwbdec.o celp_filters.o   \
 OBJS-$(CONFIG_AMV_ENCODER)             += mjpegenc.o mjpegenc_common.o
 OBJS-$(CONFIG_ANM_DECODER)             += anm.o
 OBJS-$(CONFIG_ANSI_DECODER)            += ansi.o cga_data.o
+OBJS-$(CONFIG_APAC_DECODER)            += apac.o
 OBJS-$(CONFIG_APE_DECODER)             += apedec.o
 OBJS-$(CONFIG_APTX_DECODER)            += aptxdec.o aptx.o
 OBJS-$(CONFIG_APTX_ENCODER)            += aptxenc.o aptx.o
diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
index 447225e26b..fc88e25fda 100644
--- a/libavcodec/allcodecs.c
+++ b/libavcodec/allcodecs.c
@@ -432,6 +432,7 @@ extern const FFCodec ff_alac_decoder;
 extern const FFCodec ff_als_decoder;
 extern const FFCodec ff_amrnb_decoder;
 extern const FFCodec ff_amrwb_decoder;
+extern const FFCodec ff_apac_decoder;
 extern const FFCodec ff_ape_decoder;
 extern const FFCodec ff_aptx_encoder;
 extern const FFCodec ff_aptx_decoder;
diff --git a/libavcodec/apac.c b/libavcodec/apac.c
new file mode 100644
index 0000000000..2dc9aacd44
--- /dev/null
+++ b/libavcodec/apac.c
@@ -0,0 +1,269 @@
+/*
+ * APAC audio decoder
+ *
+ * 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/audio_fifo.h"
+#include "libavutil/internal.h"
+#include "libavutil/intreadwrite.h"
+#include "avcodec.h"
+#include "codec_internal.h"
+#include "decode.h"
+#include "get_bits.h"
+
+typedef struct ChContext {
+    int have_code;
+    int last_sample;
+    int last_delta;
+    int bit_length;
+    int block_length;
+    uint8_t block[32 * 2];
+    AVAudioFifo *samples;
+} ChContext;
+
+typedef struct APACContext {
+    GetBitContext gb;
+    int skip;
+
+    int cur_ch;
+    ChContext ch[2];
+
+    uint8_t *bitstream;
+    int64_t max_framesize;
+    int bitstream_size;
+    int bitstream_index;
+} APACContext;
+
+static av_cold int apac_close(AVCodecContext *avctx)
+{
+    APACContext *s = avctx->priv_data;
+
+    av_freep(&s->bitstream);
+    s->bitstream_size = 0;
+
+    for (int ch = 0; ch < avctx->ch_layout.nb_channels; ch++) {
+        ChContext *c = &s->ch[ch];
+
+        av_audio_fifo_free(c->samples);
+    }
+
+    return 0;
+}
+
+static av_cold int apac_init(AVCodecContext *avctx)
+{
+    APACContext *s = avctx->priv_data;
+
+    if (avctx->bits_per_coded_sample > 8)
+        avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
+    else
+        avctx->sample_fmt = AV_SAMPLE_FMT_U8P;
+
+    if (avctx->ch_layout.nb_channels < 1 ||
+        avctx->ch_layout.nb_channels > 2)
+        return AVERROR_INVALIDDATA;
+
+    for (int ch = 0; ch < avctx->ch_layout.nb_channels; ch++) {
+        ChContext *c = &s->ch[ch];
+
+        c->bit_length = avctx->bits_per_coded_sample;
+        c->block_length = 8;
+        c->have_code = 0;
+        c->samples = av_audio_fifo_alloc(avctx->sample_fmt, 1, 1024);
+        if (!c->samples)
+            return AVERROR(ENOMEM);
+    }
+
+    s->max_framesize = 1024;
+    s->bitstream = av_realloc_f(s->bitstream, s->max_framesize + AV_INPUT_BUFFER_PADDING_SIZE, sizeof(*s->bitstream));
+    if (!s->bitstream)
+        return AVERROR(ENOMEM);
+
+    return 0;
+}
+
+static int get_code(ChContext *c, GetBitContext *gb)
+{
+    if (get_bits1(gb)) {
+        int code = get_bits(gb, 2);
+
+        switch (code) {
+        case 0:
+            c->bit_length--;
+            break;
+        case 1:
+            c->bit_length++;
+            break;
+        case 2:
+            c->bit_length = get_bits(gb, 5);
+            break;
+        case 3:
+            c->block_length = get_bits(gb, 4);
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
+static int apac_decode(AVCodecContext *avctx, AVFrame *frame,
+                       int *got_frame_ptr, AVPacket *pkt)
+{
+    APACContext *s = avctx->priv_data;
+    GetBitContext *gb = &s->gb;
+    int ret, n, buf_size, input_buf_size;
+    const uint8_t *buf;
+    int nb_samples;
+
+    if (!pkt->size && s->bitstream_size <= 0) {
+        *got_frame_ptr = 0;
+        return 0;
+    }
+
+    buf_size = pkt->size;
+    input_buf_size = buf_size;
+
+    if (s->bitstream_index > 0 && s->bitstream_size > 0) {
+        memmove(s->bitstream, &s->bitstream[s->bitstream_index], s->bitstream_size);
+        s->bitstream_index = 0;
+    }
+
+    if (s->bitstream_index + s->bitstream_size + buf_size > s->max_framesize) {
+        s->bitstream = av_realloc_f(s->bitstream, s->bitstream_index +
+                                    s->bitstream_size +
+                                    buf_size + AV_INPUT_BUFFER_PADDING_SIZE,
+                                    sizeof(*s->bitstream));
+        if (!s->bitstream)
+            return AVERROR(ENOMEM);
+        s->max_framesize = s->bitstream_index + s->bitstream_size + buf_size;
+    }
+    if (pkt->data)
+        memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size], pkt->data, buf_size);
+    buf                = &s->bitstream[s->bitstream_index];
+    buf_size          += s->bitstream_size;
+    s->bitstream_size  = buf_size;
+
+    frame->nb_samples = s->bitstream_size * 16 * 8;
+    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
+        return ret;
+
+    if ((ret = init_get_bits8(gb, buf, buf_size)) < 0)
+        return ret;
+
+    skip_bits(gb, s->skip);
+    s->skip = 0;
+
+    while (get_bits_left(gb) > 0) {
+        for (int ch = s->cur_ch; ch < avctx->ch_layout.nb_channels; ch++) {
+            ChContext *c = &s->ch[ch];
+            int16_t *dst16 = (int16_t *)c->block;
+            uint8_t *dst8 = (uint8_t *)c->block;
+            void *samples[4];
+
+            samples[0] = &c->block[0];
+            if (get_bits_left(gb) < 16 && pkt->size) {
+                s->cur_ch = ch;
+                goto end;
+            }
+
+            if (!c->have_code && get_code(c, gb))
+                get_code(c, gb);
+            c->have_code = 0;
+
+            if (c->block_length <= 0)
+                continue;
+
+            if (c->bit_length < 0 ||
+                c->bit_length > 17) {
+                c->bit_length = avctx->bits_per_coded_sample;
+                return AVERROR_INVALIDDATA;
+            }
+
+            if (get_bits_left(gb) < c->block_length * c->bit_length && pkt->size) {
+                c->have_code = 1;
+                s->cur_ch = ch;
+                goto end;
+            }
+
+            for (int i = 0; i < c->block_length; i++) {
+                int val = get_bits_long(gb, c->bit_length);
+                int delta = (val & 1) ? ~(val >> 1) : (val >> 1);
+                int sample;
+
+                delta += c->last_delta;
+                sample = c->last_sample + delta;
+                c->last_delta = delta;
+                c->last_sample = sample;
+
+                switch (avctx->sample_fmt) {
+                case AV_SAMPLE_FMT_S16P:
+                    dst16[i] = sample;
+                    break;
+                case AV_SAMPLE_FMT_U8P:
+                    dst8[i] = sample;
+                    break;
+                }
+            }
+
+            av_audio_fifo_write(c->samples, samples, c->block_length);
+        }
+
+        s->cur_ch = 0;
+    }
+end:
+    nb_samples = frame->nb_samples;
+    for (int ch = 0; ch < avctx->ch_layout.nb_channels; ch++)
+        nb_samples = FFMIN(av_audio_fifo_size(s->ch[ch].samples), nb_samples);
+
+    frame->nb_samples = nb_samples;
+    for (int ch = 0; ch < avctx->ch_layout.nb_channels; ch++) {
+        void *samples[1] = { frame->extended_data[ch] };
+        av_audio_fifo_read(s->ch[ch].samples, samples, nb_samples);
+    }
+
+    s->skip = get_bits_count(gb) - 8 * (get_bits_count(gb) / 8);
+    n = get_bits_count(gb) / 8;
+
+    if (nb_samples > 0 || pkt->size)
+        *got_frame_ptr = 1;
+
+    if (s->bitstream_size > 0) {
+        s->bitstream_index += n;
+        s->bitstream_size  -= n;
+        return input_buf_size;
+    }
+    return n;
+}
+
+const FFCodec ff_apac_decoder = {
+    .p.name           = "apac",
+    CODEC_LONG_NAME("Marian's A-pac audio"),
+    .p.type           = AVMEDIA_TYPE_AUDIO,
+    .p.id             = AV_CODEC_ID_APAC,
+    .priv_data_size   = sizeof(APACContext),
+    .init             = apac_init,
+    FF_CODEC_DECODE_CB(apac_decode),
+    .close            = apac_close,
+    .p.capabilities   = AV_CODEC_CAP_DELAY |
+                        AV_CODEC_CAP_DR1 |
+                        AV_CODEC_CAP_SUBFRAMES,
+    .caps_internal    = FF_CODEC_CAP_INIT_CLEANUP,
+    .p.sample_fmts    = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_U8P,
+                                                        AV_SAMPLE_FMT_S16P,
+                                                        AV_SAMPLE_FMT_NONE },
+};
diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
index 648c518b3c..e8e1529401 100644
--- a/libavcodec/codec_desc.c
+++ b/libavcodec/codec_desc.c
@@ -3304,6 +3304,13 @@ static const AVCodecDescriptor codec_descriptors[] = {
         .long_name = NULL_IF_CONFIG_SMALL("Micronas SC-4 Audio"),
         .props     = AV_CODEC_PROP_LOSSY | AV_CODEC_PROP_INTRA_ONLY,
     },
+    {
+        .id        = AV_CODEC_ID_APAC,
+        .type      = AVMEDIA_TYPE_AUDIO,
+        .name      = "apac",
+        .long_name = NULL_IF_CONFIG_SMALL("Marian's A-pac audio"),
+        .props     = AV_CODEC_PROP_INTRA_ONLY | AV_CODEC_PROP_LOSSLESS,
+    },
 
     /* subtitle codecs */
     {
diff --git a/libavcodec/codec_id.h b/libavcodec/codec_id.h
index bc8226ff07..9c01ea9750 100644
--- a/libavcodec/codec_id.h
+++ b/libavcodec/codec_id.h
@@ -529,6 +529,7 @@ enum AVCodecID {
     AV_CODEC_ID_DFPWM,
     AV_CODEC_ID_BONK,
     AV_CODEC_ID_MISC4,
+    AV_CODEC_ID_APAC,
 
     /* subtitle codecs */
     AV_CODEC_ID_FIRST_SUBTITLE = 0x17000,          ///< A dummy ID pointing at the start of subtitle codecs.
-- 
2.37.2


[-- Attachment #3: 0002-avformat-add-APAC-demuxer.patch --]
[-- Type: text/x-patch, Size: 4762 bytes --]

From d2d7ed7a0539424fe3dd72fdc68a95840d54123b Mon Sep 17 00:00:00 2001
From: Paul B Mahol <onemda@gmail.com>
Date: Mon, 19 Sep 2022 22:05:20 +0200
Subject: [PATCH 2/2] avformat: add APAC demuxer

Signed-off-by: Paul B Mahol <onemda@gmail.com>
---
 libavformat/Makefile     |  1 +
 libavformat/allformats.c |  1 +
 libavformat/apac.c       | 85 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 87 insertions(+)
 create mode 100644 libavformat/apac.c

diff --git a/libavformat/Makefile b/libavformat/Makefile
index 19deb33c2e..d669dc8f44 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -101,6 +101,7 @@ OBJS-$(CONFIG_AMRNB_DEMUXER)             += amr.o rawdec.o
 OBJS-$(CONFIG_AMRWB_DEMUXER)             += amr.o rawdec.o
 OBJS-$(CONFIG_AMV_MUXER)                 += amvenc.o
 OBJS-$(CONFIG_ANM_DEMUXER)               += anm.o
+OBJS-$(CONFIG_APAC_DEMUXER)              += apac.o rawdec.o
 OBJS-$(CONFIG_APC_DEMUXER)               += apc.o
 OBJS-$(CONFIG_APE_DEMUXER)               += ape.o apetag.o img2.o
 OBJS-$(CONFIG_APM_DEMUXER)               += apm.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index a545b5ff45..47c419a009 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -52,6 +52,7 @@ extern const AVInputFormat  ff_amrnb_demuxer;
 extern const AVInputFormat  ff_amrwb_demuxer;
 extern const AVOutputFormat ff_amv_muxer;
 extern const AVInputFormat  ff_anm_demuxer;
+extern const AVInputFormat  ff_apac_demuxer;
 extern const AVInputFormat  ff_apc_demuxer;
 extern const AVInputFormat  ff_ape_demuxer;
 extern const AVInputFormat  ff_apm_demuxer;
diff --git a/libavformat/apac.c b/libavformat/apac.c
new file mode 100644
index 0000000000..4d484221fe
--- /dev/null
+++ b/libavformat/apac.c
@@ -0,0 +1,85 @@
+/*
+ * APAC 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 "demux.h"
+#include "internal.h"
+#include "rawdec.h"
+
+static int apac_probe(const AVProbeData *p)
+{
+    if (AV_RB32(p->buf) == MKBETAG('A','P','A','C') &&
+        AV_RB32(p->buf + 8) == MKBETAG('P','R','O','F') &&
+        AV_RB32(p->buf + 12) == MKBETAG('N','A','D',' '))
+        return AVPROBE_SCORE_MAX;
+
+    return 0;
+}
+
+static int apac_read_header(AVFormatContext *s)
+{
+    AVIOContext *pb = s->pb;
+    uint32_t chunk_size;
+    AVStream *st;
+    int64_t pos;
+
+    avio_skip(pb, 16);
+    chunk_size = avio_rl32(pb);
+    avio_skip(pb, chunk_size);
+    if (avio_rb32(pb) != MKBETAG('P','F','M','T'))
+        return AVERROR_INVALIDDATA;
+    chunk_size = avio_rl32(pb);
+    pos = avio_tell(pb);
+    avio_skip(pb, 2);
+    st = avformat_new_stream(s, NULL);
+    if (!st)
+        return AVERROR(ENOMEM);
+    st->codecpar->codec_type  = AVMEDIA_TYPE_AUDIO;
+    st->codecpar->codec_id    = AV_CODEC_ID_APAC;
+    st->codecpar->ch_layout.nb_channels = avio_rl16(pb);
+    st->codecpar->sample_rate = avio_rl32(pb);
+    if (st->codecpar->ch_layout.nb_channels <= 0 ||
+        st->codecpar->sample_rate <= 0)
+        return AVERROR_INVALIDDATA;
+    avio_skip(pb, 2);
+    st->codecpar->bits_per_coded_sample = avio_rl16(pb);
+    avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
+    avio_skip(pb, (chunk_size + pos) - avio_tell(pb) + (chunk_size & 1));
+    if (avio_rb32(pb) != MKBETAG('P','A','D',' '))
+        return AVERROR_INVALIDDATA;
+    avio_skip(pb, 4);
+
+    return 0;
+}
+
+const AVInputFormat ff_apac_demuxer = {
+    .name           = "apac",
+    .long_name      = NULL_IF_CONFIG_SMALL("raw APAC"),
+    .read_probe     = apac_probe,
+    .read_header    = apac_read_header,
+    .read_packet    = ff_raw_read_partial_packet,
+    .extensions     = "apc",
+    .flags          = AVFMT_NOBINSEARCH | AVFMT_NOGENSEARCH | AVFMT_NO_BYTE_SEEK | AVFMT_NOTIMESTAMPS,
+    .raw_codec_id   = AV_CODEC_ID_APAC,
+    .priv_data_size = sizeof(FFRawDemuxerContext),
+    .priv_class     = &ff_raw_demuxer_class,
+};
-- 
2.37.2


[-- Attachment #4: Type: text/plain, Size: 251 bytes --]

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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [FFmpeg-devel] [PATCH] A-pac demuxer and decoder
  2022-09-21  7:23 [FFmpeg-devel] [PATCH] A-pac demuxer and decoder Paul B Mahol
@ 2022-09-23 17:48 ` Paul B Mahol
  2022-09-23 18:31 ` James Almer
  1 sibling, 0 replies; 3+ messages in thread
From: Paul B Mahol @ 2022-09-23 17:48 UTC (permalink / raw)
  To: FFmpeg development discussions and patches

On 9/21/22, Paul B Mahol <onemda@gmail.com> wrote:
> Patches attached.
>

WIll apply soon.
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To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [FFmpeg-devel] [PATCH] A-pac demuxer and decoder
  2022-09-21  7:23 [FFmpeg-devel] [PATCH] A-pac demuxer and decoder Paul B Mahol
  2022-09-23 17:48 ` Paul B Mahol
@ 2022-09-23 18:31 ` James Almer
  1 sibling, 0 replies; 3+ messages in thread
From: James Almer @ 2022-09-23 18:31 UTC (permalink / raw)
  To: ffmpeg-devel

On 9/21/2022 4:23 AM, Paul B Mahol wrote:
> Patches attached.

[...]

> +static av_cold int apac_close(AVCodecContext *avctx)
> +{
> +    APACContext *s = avctx->priv_data;
> +
> +    av_freep(&s->bitstream);
> +    s->bitstream_size = 0;
> +
> +    for (int ch = 0; ch < avctx->ch_layout.nb_channels; ch++) {

for (int ch = 0; ch < FF_ARRAY_ELEMS(s->ch); ch++)

As Andreas mentioned on IRC, this will crash if you try to initialize 
the decoder by setting more than 2 channels otherwise.

> +        ChContext *c = &s->ch[ch];
> +
> +        av_audio_fifo_free(c->samples);
> +    }
> +
> +    return 0;
> +}

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^ permalink raw reply	[flat|nested] 3+ messages in thread

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