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FFmpeg/libavformat/rtpenc_aac.c
Martin Storsjö 4f6cd883f0 rtpenc: Don't set max_frames_per_packet based on the packet frame size or frame rate
Instead check the timestamps while muxing, to avoid buffering a
too long timestamp range into one single packet.

This makes the AMR and AAC packetization slightly less efficient,
since we set a possibly unnecessarily high max_frames_per_packet.
(These packetizers end up doing a memmove of the TOC bytes if
sending a packet before max_frames_per_packet is achieved, and
we end up setting max_frames_per_packet to a value that should
be high enough for most uses.)

All packetizers that use max_frames_per_packet now set it either
to a default value, or to a value calculated based on other
parameters, so none of them rely on the previous default setting.

For iLBC, copy one frame at a time, to allow checking the timestamp
range for each of them - basically doing potentially multiple
loops to simplify the code instead of trying to calculate the
number of frames to buffer while honoring s1->max_delay.

This is in preparation for reducing the coupling between libavformat
and libavcodec, by not having the muxers use the encoder field
frame_size (which may not be available during e.g. stream copy).

Signed-off-by: Martin Storsjö <martin@martin.st>
2015-02-28 22:54:31 +02:00

87 lines
2.7 KiB
C

/*
* copyright (c) 2007 Luca Abeni
*
* This file is part of Libav.
*
* Libav 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,
* 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
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/intreadwrite.h"
#include "avformat.h"
#include "rtpenc.h"
void ff_rtp_send_aac(AVFormatContext *s1, const uint8_t *buff, int size)
{
RTPMuxContext *s = s1->priv_data;
AVStream *st = s1->streams[0];
const int max_au_headers_size = 2 + 2 * s->max_frames_per_packet;
int len, max_packet_size = s->max_payload_size - max_au_headers_size;
uint8_t *p;
/* skip ADTS header, if present */
if ((s1->streams[0]->codec->extradata_size) == 0) {
size -= 7;
buff += 7;
}
/* test if the packet must be sent */
len = (s->buf_ptr - s->buf);
if (s->num_frames &&
(s->num_frames == s->max_frames_per_packet ||
(len + size) > s->max_payload_size ||
av_compare_ts(s->cur_timestamp - s->timestamp, st->time_base,
s1->max_delay, AV_TIME_BASE_Q) >= 0)) {
int au_size = s->num_frames * 2;
p = s->buf + max_au_headers_size - au_size - 2;
if (p != s->buf) {
memmove(p + 2, s->buf + 2, au_size);
}
/* Write the AU header size */
AV_WB16(p, au_size * 8);
ff_rtp_send_data(s1, p, s->buf_ptr - p, 1);
s->num_frames = 0;
}
if (s->num_frames == 0) {
s->buf_ptr = s->buf + max_au_headers_size;
s->timestamp = s->cur_timestamp;
}
if (size <= max_packet_size) {
p = s->buf + s->num_frames++ * 2 + 2;
AV_WB16(p, size * 8);
memcpy(s->buf_ptr, buff, size);
s->buf_ptr += size;
} else {
int au_size = size;
max_packet_size = s->max_payload_size - 4;
p = s->buf;
AV_WB16(p, 2 * 8);
while (size > 0) {
len = FFMIN(size, max_packet_size);
AV_WB16(&p[2], au_size * 8);
memcpy(p + 4, buff, len);
ff_rtp_send_data(s1, p, len + 4, len == size);
size -= len;
buff += len;
}
}
}