* Copyright (C) 2009 Justin Ruggles
* Copyright (c) 2009 Xuggle Incorporated
*
- * This file is part of Libav.
+ * This file is part of FFmpeg.
*
- * Libav is free software; you can redistribute it and/or
+ * 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.
*
- * Libav is distributed in the hope that it will be useful,
+ * 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 Libav; if not, write to the Free Software
+ * License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
* sometimes desirable to use multiple frames-per-packet to reduce the
* amount of container overhead. This can be done by setting the
* 'frames_per_packet' option to a value 1 to 8.
+ *
+ *
+ * Optional features
+ * Speex encoder supports several optional features, which can be useful
+ * for some conditions.
+ *
+ * Voice Activity Detection
+ * When enabled, voice activity detection detects whether the audio
+ * being encoded is speech or silence/background noise. VAD is always
+ * implicitly activated when encoding in VBR, so the option is only useful
+ * in non-VBR operation. In this case, Speex detects non-speech periods and
+ * encodes them with just enough bits to reproduce the background noise.
+ *
+ * Discontinuous Transmission (DTX)
+ * DTX is an addition to VAD/VBR operation, that allows to stop transmitting
+ * completely when the background noise is stationary.
+ * In file-based operation only 5 bits are used for such frames.
*/
#include <speex/speex.h>
#include "internal.h"
#include "audio_frame_queue.h"
+/* TODO: Think about converting abr, vad, dtx and such flags to a bit field */
typedef struct {
AVClass *class; ///< AVClass for private options
SpeexBits bits; ///< libspeex bitwriter context
int cbr_quality; ///< CBR quality 0 to 10
int abr; ///< flag to enable ABR
int vad; ///< flag to enable VAD
+ int dtx; ///< flag to enable DTX
int pkt_frame_count; ///< frame count for the current packet
AudioFrameQueue afq; ///< frame queue
} LibSpeexEncContext;
av_log(avctx, AV_LOG_DEBUG, "packet size: %d\n",
avctx->frame_size * s->frames_per_packet);
av_log(avctx, AV_LOG_DEBUG, "voice activity detection: %d\n", s->vad);
+ av_log(avctx, AV_LOG_DEBUG, "discontinuous transmission: %d\n", s->dtx);
}
static av_cold int encode_init(AVCodecContext *avctx)
if (s->vad)
speex_encoder_ctl(s->enc_state, SPEEX_SET_VAD, &s->vad);
+ /* Activiting Discontinuous Transmission */
+ if (s->dtx) {
+ speex_encoder_ctl(s->enc_state, SPEEX_SET_DTX, &s->dtx);
+ if ( !(s->abr || s->vad || s->header.vbr))
+ av_log(avctx, AV_LOG_WARNING, "DTX is not much of use without ABR, VAD or VBR\n");
+ }
+
/* set encoding complexity */
if (avctx->compression_level > FF_COMPRESSION_DEFAULT) {
complexity = av_clip(avctx->compression_level, 0, 10);
/* write output if all frames for the packet have been encoded */
if (s->pkt_frame_count == s->frames_per_packet) {
s->pkt_frame_count = 0;
- if ((ret = ff_alloc_packet(avpkt, speex_bits_nbytes(&s->bits)))) {
- av_log(avctx, AV_LOG_ERROR, "Error getting output packet\n");
+ if ((ret = ff_alloc_packet2(avctx, avpkt, speex_bits_nbytes(&s->bits))))
return ret;
- }
ret = speex_bits_write(&s->bits, avpkt->data, avpkt->size);
speex_bits_reset(&s->bits);
{ "cbr_quality", "Set quality value (0 to 10) for CBR", OFFSET(cbr_quality), AV_OPT_TYPE_INT, { .i64 = 8 }, 0, 10, AE },
{ "frames_per_packet", "Number of frames to encode in each packet", OFFSET(frames_per_packet), AV_OPT_TYPE_INT, { .i64 = 1 }, 1, 8, AE },
{ "vad", "Voice Activity Detection", OFFSET(vad), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, AE },
+ { "dtx", "Discontinuous Transmission", OFFSET(dtx), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, AE },
{ NULL },
};