generate adts frame headers if required

Originally committed as revision 4970 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 128 insertions, 0 deletions

diff --git a/libavformat/adtsenc.c b/libavformat/adtsenc.c
new file mode 100644
index 0000000000..55f8831af1
--- /dev/null
+++ b/libavformat/adtsenc.c
@@ -0,0 +1,128 @@
+/*
+ * ADTS muxer.
+ * Copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@smartjog.com>
+ *                    Mans Rullgard <mru@inprovide.com>
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include "avformat.h"
+#include "bitstream.h"
+
+#define ADTS_HEADER_SIZE 7
+
+typedef struct {
+    int write_adts;
+    int objecttype;
+    int sample_rate_index;
+    int channel_conf;
+} ADTSContext;
+
+static int decode_extradata(ADTSContext *adts, uint8_t *buf, int size)
+{
+    GetBitContext gb;
+
+    init_get_bits(&gb, buf, size * 8);
+    adts->objecttype = get_bits(&gb, 5) - 1;
+    adts->sample_rate_index = get_bits(&gb, 4);
+    adts->channel_conf = get_bits(&gb, 4);
+
+    adts->write_adts = 1;
+
+    return 0;
+}
+
+static int adts_write_header(AVFormatContext *s)
+{
+    ADTSContext *adts = s->priv_data;
+    AVCodecContext *avc = s->streams[0]->codec;
+
+    if(avc->extradata_size > 0)
+        decode_extradata(adts, avc->extradata, avc->extradata_size);
+
+    return 0;
+}
+
+static int adts_write_frame_header(AVFormatContext *s, int size)
+{
+    ADTSContext *ctx = s->priv_data;
+    PutBitContext pb;
+    uint8_t buf[ADTS_HEADER_SIZE];
+
+    init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
+
+    /* adts_fixed_header */
+    put_bits(&pb, 12, 0xfff);   /* syncword */
+    put_bits(&pb, 1, 0);        /* ID */
+    put_bits(&pb, 2, 0);        /* layer */
+    put_bits(&pb, 1, 1);        /* protection_absent */
+    put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
+    put_bits(&pb, 4, ctx->sample_rate_index);
+    put_bits(&pb, 1, 0);        /* private_bit */
+    put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
+    put_bits(&pb, 1, 0);        /* original_copy */
+    put_bits(&pb, 1, 0);        /* home */
+
+    /* adts_variable_header */
+    put_bits(&pb, 1, 0);        /* copyright_identification_bit */
+    put_bits(&pb, 1, 0);        /* copyright_identification_start */
+    put_bits(&pb, 13, ADTS_HEADER_SIZE + size); /* aac_frame_length */
+    put_bits(&pb, 11, 0x7ff);   /* adts_buffer_fullness */
+    put_bits(&pb, 2, 0);        /* number_of_raw_data_blocks_in_frame */
+
+    flush_put_bits(&pb);
+    put_buffer(&s->pb, buf, ADTS_HEADER_SIZE);
+
+    return 0;
+}
+
+static int adts_write_trailer(AVFormatContext *s)
+{
+    return 0;
+}
+
+static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    ADTSContext *adts = s->priv_data;
+    ByteIOContext *pb = &s->pb;
+
+    if(adts->write_adts)
+        adts_write_frame_header(s, pkt->size);
+    put_buffer(pb, pkt->data, pkt->size);
+
+    return 0;
+}
+
+#ifdef CONFIG_MUXERS
+static AVOutputFormat adts_oformat = {
+    "adts",
+    "ADTS AAC",
+    "audio/aac",
+    "aac",
+    sizeof(ADTSContext),
+    CODEC_ID_AAC,
+    CODEC_ID_NONE,
+    adts_write_header,
+    adts_write_packet,
+    adts_write_trailer,
+};
+#endif //CONFIG_MUXERS
+
+int ff_adts_init(void)
+{
+#ifdef CONFIG_MUXERS
+    av_register_output_format(&adts_oformat);
+#endif //CONFIG_MUXERS
+    return 0;
+}