avcodec: add truehd_core bitstream filter

Changelog

@@ -7,6 +7,7 @@ version <next>:
 - dedot filter
 - chromashift and rgbashift filters
 - freezedetect filter
+- truehd_core bitstream filter
 
 
 version 4.1:

configure

@@ -3046,6 +3046,7 @@ hevc_metadata_bsf_select="cbs_h265"
 mjpeg2jpeg_bsf_select="jpegtables"
 mpeg2_metadata_bsf_select="cbs_mpeg2"
 trace_headers_bsf_select="cbs"
+truehd_core_bsf_select="mlp_parser"
 vp9_metadata_bsf_select="cbs_vp9"
 
 # external libraries

doc/bitstream_filters.texi

@@ -634,6 +634,10 @@ This can be useful for debugging low-level stream issues.
 
 Supports H.264, H.265, MPEG-2 and VP9.
 
+@section truehd_core
+
+Extract the core from a TrueHD stream, dropping ATMOS data.
+
 @section vp9_metadata
 
 Modify metadata embedded in a VP9 stream.

libavcodec/Makefile

@@ -1085,6 +1085,7 @@ OBJS-$(CONFIG_PRORES_METADATA_BSF)        += prores_metadata_bsf.o
 OBJS-$(CONFIG_REMOVE_EXTRADATA_BSF)       += remove_extradata_bsf.o
 OBJS-$(CONFIG_TEXT2MOVSUB_BSF)            += movsub_bsf.o
 OBJS-$(CONFIG_TRACE_HEADERS_BSF)          += trace_headers_bsf.o
+OBJS-$(CONFIG_TRUEHD_CORE_BSF)            += truehd_core_bsf.o mlp_parser.o mlp.o
 OBJS-$(CONFIG_VP9_METADATA_BSF)           += vp9_metadata_bsf.o
 OBJS-$(CONFIG_VP9_RAW_REORDER_BSF)        += vp9_raw_reorder_bsf.o
 OBJS-$(CONFIG_VP9_SUPERFRAME_BSF)         += vp9_superframe_bsf.o

libavcodec/bitstream_filters.c

@@ -51,6 +51,7 @@ extern const AVBitStreamFilter ff_prores_metadata_bsf;
 extern const AVBitStreamFilter ff_remove_extradata_bsf;
 extern const AVBitStreamFilter ff_text2movsub_bsf;
 extern const AVBitStreamFilter ff_trace_headers_bsf;
+extern const AVBitStreamFilter ff_truehd_core_bsf;
 extern const AVBitStreamFilter ff_vp9_metadata_bsf;
 extern const AVBitStreamFilter ff_vp9_raw_reorder_bsf;
 extern const AVBitStreamFilter ff_vp9_superframe_bsf;

libavcodec/truehd_core_bsf.c

@@ -0,0 +1,184 @@
+/*
+ * Copyright (c) 2018 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 "avcodec.h"
+#include "bsf.h"
+#include "get_bits.h"
+#include "mlp_parser.h"
+#include "mlp.h"
+
+typedef struct AccessUnit {
+    uint8_t bits[4];
+    uint16_t offset;
+    uint16_t optional;
+} AccessUnit;
+
+typedef struct TrueHDCoreContext {
+    const AVClass *class;
+
+    MLPHeaderInfo hdr;
+} TrueHDCoreContext;
+
+static int truehd_core_filter(AVBSFContext *ctx, AVPacket *out)
+{
+    TrueHDCoreContext *s = ctx->priv_data;
+    GetBitContext gbc;
+    AccessUnit units[MAX_SUBSTREAMS];
+    AVPacket *in;
+    int ret, i, size, last_offset = 0;
+    int in_size, out_size;
+    int have_header = 0;
+    int substream_bits = 0;
+    int start, end;
+    uint16_t dts;
+
+    ret = ff_bsf_get_packet(ctx, &in);
+    if (ret < 0)
+        return ret;
+
+    if (in->size < 4)
+        goto fail;
+
+    ret = init_get_bits(&gbc, in->data, 32);
+    if (ret < 0)
+        goto fail;
+
+    skip_bits(&gbc, 4);
+    in_size = get_bits(&gbc, 12) * 2;
+    if (in_size < 4 || in_size > in->size)
+        goto fail;
+
+    out_size = in_size;
+    dts = get_bits(&gbc, 16);
+
+    ret = init_get_bits8(&gbc, in->data + 4, in->size - 4);
+    if (ret < 0)
+        goto fail;
+
+    if (show_bits_long(&gbc, 32) == 0xf8726fba) {
+        if ((ret = ff_mlp_read_major_sync(ctx, &s->hdr, &gbc)) != 0)
+            goto fail;
+        have_header = 1;
+    }
+
+    if (s->hdr.num_substreams > MAX_SUBSTREAMS)
+        goto fail;
+
+    start = get_bits_count(&gbc);
+    for (i = 0; i < s->hdr.num_substreams; i++) {
+        for (int j = 0; j < 4; j++)
+            units[i].bits[j] = get_bits1(&gbc);
+
+        units[i].offset = get_bits(&gbc, 12) * 2;
+        if (i < FFMIN(s->hdr.num_substreams, 3)) {
+            last_offset = units[i].offset;
+            substream_bits += 16;
+        }
+
+        if (units[i].bits[0]) {
+            units[i].optional = get_bits(&gbc, 16);
+            if (i < FFMIN(s->hdr.num_substreams, 3))
+                substream_bits += 16;
+        }
+    }
+    end = get_bits_count(&gbc);
+
+    size = ((end + 7) >> 3) + 4 + last_offset;
+    if (size >= 0 && size <= in->size)
+        out_size = size;
+    if (out_size < in_size) {
+        int bpos = 0, reduce = (end - start - substream_bits) >> 4;
+        uint16_t parity_nibble = 0;
+        uint16_t auheader;
+
+        ret = av_new_packet(out, out_size);
+        if (ret < 0)
+            goto fail;
+
+        AV_WB16(out->data + 2, dts);
+        parity_nibble = dts;
+        out->size -= reduce * 2;
+        parity_nibble ^= out->size / 2;
+
+        if (have_header) {
+            memcpy(out->data + 4, in->data + 4, 28);
+            out->data[16 + 4] = (out->data[16 + 4] & 0x0f) | (FFMIN(s->hdr.num_substreams, 3) << 4);
+            out->data[25 + 4] = out->data[25 + 4] & 0xfe;
+            out->data[26 + 4] = 0xff;
+            out->data[27 + 4] = 0xff;
+            AV_WL16(out->data + 4 + 26, ff_mlp_checksum16(out->data + 4, 26));
+        }
+
+        for (i = 0; i < FFMIN(s->hdr.num_substreams, 3); i++) {
+            uint16_t substr_hdr = 0;
+
+            substr_hdr |= (units[i].bits[0] << 15);
+            substr_hdr |= (units[i].bits[1] << 14);
+            substr_hdr |= (units[i].bits[2] << 13);
+            substr_hdr |= (units[i].bits[3] << 12);
+            substr_hdr |= (units[i].offset / 2) & 0x0FFF;
+
+            AV_WB16(out->data + have_header * 28 + 4 + bpos, substr_hdr);
+
+            parity_nibble ^= out->data[have_header * 28 + 4 + bpos++];
+            parity_nibble ^= out->data[have_header * 28 + 4 + bpos++];
+
+            if (units[i].bits[0]) {
+                AV_WB16(out->data + have_header * 28 + 4 + bpos, units[i].optional);
+
+                parity_nibble ^= out->data[have_header * 28 + 4 + bpos++];
+                parity_nibble ^= out->data[have_header * 28 + 4 + bpos++];
+            }
+        }
+
+        parity_nibble ^= parity_nibble >> 8;
+        parity_nibble ^= parity_nibble >> 4;
+        parity_nibble &= 0xF;
+
+        memcpy(out->data + have_header * 28 + 4 + bpos,
+               in->data + 4 + (end >> 3),
+               out_size - (4 + (end >> 3)));
+        auheader  = (parity_nibble ^ 0xF) << 12;
+        auheader |= (out->size / 2) & 0x0fff;
+        AV_WB16(out->data, auheader);
+
+        ret = av_packet_copy_props(out, in);
+    } else {
+        av_packet_move_ref(out, in);
+    }
+
+fail:
+    if (ret < 0)
+        av_packet_unref(out);
+    av_packet_free(&in);
+
+    return ret;
+}
+
+static const enum AVCodecID codec_ids[] = {
+    AV_CODEC_ID_TRUEHD, AV_CODEC_ID_NONE,
+};
+
+const AVBitStreamFilter ff_truehd_core_bsf = {
+    .name           = "truehd_core",
+    .priv_data_size = sizeof(TrueHDCoreContext),
+    .filter         = truehd_core_filter,
+    .codec_ids      = codec_ids,
+};

libavcodec/version.h

@@ -28,7 +28,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVCODEC_VERSION_MAJOR  58
-#define LIBAVCODEC_VERSION_MINOR  39
+#define LIBAVCODEC_VERSION_MINOR  40
 #define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \