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obs-studio/plugins/obs-outputs/flv-mux.c
jp9000 4a5ac39749 libobs: Fix starting video packet offset in outputs 
(This commit also modifies the obs-outputs module)

The first video packet video offset (the value used to set the starting
point of video data) would be set to the DTS value of the first video
packet.  However, when b-frames are used, the first DTS value will be
negative.  This was originally done because FLV muxing requires that the
first packet's DTS start from 0.  Unfortunately, this would also
effectively cause the first packet's PTS/DTS value to be shifted forward
by the negative amount, which would cause video sync to be off by a
video frame or two.

This fixes it to start at the PTS value instead and preserve any
negative offsets.  Additionally, the FLV muxing code has been fixed to
ensure that it adjusts the starting video DTS to 0, and now correctly
adjusts the first audio packet's timestamp according to that DTS as well
(which it didn't do before).
2017-10-02 07:36:02 -07:00

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6.7 KiB
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/******************************************************************************
Copyright (C) 2014 by Hugh Bailey <obs.jim@gmail.com>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
******************************************************************************/
#include <obs.h>
#include <stdio.h>
#include <util/dstr.h>
#include <util/array-serializer.h>
#include "flv-mux.h"
#include "obs-output-ver.h"
#include "rtmp-helpers.h"
/* TODO: FIXME: this is currently hard-coded to h264 and aac! ..not that we'll
* use anything else for a long time. */
//#define DEBUG_TIMESTAMPS
//#define WRITE_FLV_HEADER
#define VIDEO_HEADER_SIZE 5
static inline double encoder_bitrate(obs_encoder_t *encoder)
{
obs_data_t *settings = obs_encoder_get_settings(encoder);
double bitrate = obs_data_get_double(settings, "bitrate");
obs_data_release(settings);
return bitrate;
}
#define FLV_INFO_SIZE_OFFSET 42
void write_file_info(FILE *file, int64_t duration_ms, int64_t size)
{
char buf[64];
char *enc = buf;
char *end = enc + sizeof(buf);
fseek(file, FLV_INFO_SIZE_OFFSET, SEEK_SET);
enc_num_val(&enc, end, "duration", (double)duration_ms / 1000.0);
enc_num_val(&enc, end, "fileSize", (double)size);
fwrite(buf, 1, enc - buf, file);
}
static bool build_flv_meta_data(obs_output_t *context,
uint8_t **output, size_t *size, size_t a_idx)
{
obs_encoder_t *vencoder = obs_output_get_video_encoder(context);
obs_encoder_t *aencoder = obs_output_get_audio_encoder(context, a_idx);
video_t *video = obs_encoder_video(vencoder);
audio_t *audio = obs_encoder_audio(aencoder);
char buf[4096];
char *enc = buf;
char *end = enc+sizeof(buf);
struct dstr encoder_name = {0};
if (a_idx > 0 && !aencoder)
return false;
enc_str(&enc, end, "onMetaData");
*enc++ = AMF_ECMA_ARRAY;
enc = AMF_EncodeInt32(enc, end, a_idx == 0 ? 14 : 9);
enc_num_val(&enc, end, "duration", 0.0);
enc_num_val(&enc, end, "fileSize", 0.0);
if (a_idx == 0) {
enc_num_val(&enc, end, "width",
(double)obs_encoder_get_width(vencoder));
enc_num_val(&enc, end, "height",
(double)obs_encoder_get_height(vencoder));
enc_str_val(&enc, end, "videocodecid", "avc1");
enc_num_val(&enc, end, "videodatarate",
encoder_bitrate(vencoder));
enc_num_val(&enc, end, "framerate",
video_output_get_frame_rate(video));
}
enc_str_val(&enc, end, "audiocodecid", "mp4a");
enc_num_val(&enc, end, "audiodatarate", encoder_bitrate(aencoder));
enc_num_val(&enc, end, "audiosamplerate",
(double)obs_encoder_get_sample_rate(aencoder));
enc_num_val(&enc, end, "audiosamplesize", 16.0);
enc_num_val(&enc, end, "audiochannels",
(double)audio_output_get_channels(audio));
enc_bool_val(&enc, end, "stereo",
audio_output_get_channels(audio) == 2);
dstr_printf(&encoder_name, "%s (libobs version ",
MODULE_NAME);
#ifdef HAVE_OBSCONFIG_H
dstr_cat(&encoder_name, OBS_VERSION);
#else
dstr_catf(&encoder_name, "%d.%d.%d",
LIBOBS_API_MAJOR_VER,
LIBOBS_API_MINOR_VER,
LIBOBS_API_PATCH_VER);
#endif
dstr_cat(&encoder_name, ")");
enc_str_val(&enc, end, "encoder", encoder_name.array);
dstr_free(&encoder_name);
*enc++ = 0;
*enc++ = 0;
*enc++ = AMF_OBJECT_END;
*size = enc-buf;
*output = bmemdup(buf, *size);
return true;
}
bool flv_meta_data(obs_output_t *context, uint8_t **output, size_t *size,
bool write_header, size_t audio_idx)
{
struct array_output_data data;
struct serializer s;
uint8_t *meta_data = NULL;
size_t meta_data_size;
uint32_t start_pos;
array_output_serializer_init(&s, &data);
if (!build_flv_meta_data(context, &meta_data, &meta_data_size,
audio_idx)) {
bfree(meta_data);
return false;
}
if (write_header) {
s_write(&s, "FLV", 3);
s_w8(&s, 1);
s_w8(&s, 5);
s_wb32(&s, 9);
s_wb32(&s, 0);
}
start_pos = serializer_get_pos(&s);
s_w8(&s, RTMP_PACKET_TYPE_INFO);
s_wb24(&s, (uint32_t)meta_data_size);
s_wb32(&s, 0);
s_wb24(&s, 0);
s_write(&s, meta_data, meta_data_size);
s_wb32(&s, (uint32_t)serializer_get_pos(&s) - start_pos + 4 - 1);
*output = data.bytes.array;
*size = data.bytes.num;
bfree(meta_data);
return true;
}
#ifdef DEBUG_TIMESTAMPS
static int32_t last_time = 0;
#endif
static void flv_video(struct serializer *s, int32_t dts_offset,
struct encoder_packet *packet, bool is_header)
{
int64_t offset = packet->pts - packet->dts;
int32_t time_ms = get_ms_time(packet, packet->dts) - dts_offset;
if (!packet->data || !packet->size)
return;
s_w8(s, RTMP_PACKET_TYPE_VIDEO);
#ifdef DEBUG_TIMESTAMPS
blog(LOG_DEBUG, "Video: %lu", time_ms);
if (last_time > time_ms)
blog(LOG_DEBUG, "Non-monotonic");
last_time = time_ms;
#endif
s_wb24(s, (uint32_t)packet->size + 5);
s_wb24(s, time_ms);
s_w8(s, (time_ms >> 24) & 0x7F);
s_wb24(s, 0);
/* these are the 5 extra bytes mentioned above */
s_w8(s, packet->keyframe ? 0x17 : 0x27);
s_w8(s, is_header ? 0 : 1);
s_wb24(s, get_ms_time(packet, offset));
s_write(s, packet->data, packet->size);
/* write tag size (starting byte doesn't count) */
s_wb32(s, (uint32_t)serializer_get_pos(s) + 4 - 1);
}
static void flv_audio(struct serializer *s, int32_t dts_offset,
struct encoder_packet *packet, bool is_header)
{
int32_t time_ms = get_ms_time(packet, packet->dts) - dts_offset;
if (!packet->data || !packet->size)
return;
s_w8(s, RTMP_PACKET_TYPE_AUDIO);
#ifdef DEBUG_TIMESTAMPS
blog(LOG_DEBUG, "Audio: %lu", time_ms);
if (last_time > time_ms)
blog(LOG_DEBUG, "Non-monotonic");
last_time = time_ms;
#endif
s_wb24(s, (uint32_t)packet->size + 2);
s_wb24(s, time_ms);
s_w8(s, (time_ms >> 24) & 0x7F);
s_wb24(s, 0);
/* these are the two extra bytes mentioned above */
s_w8(s, 0xaf);
s_w8(s, is_header ? 0 : 1);
s_write(s, packet->data, packet->size);
/* write tag size (starting byte doesn't count) */
s_wb32(s, (uint32_t)serializer_get_pos(s) + 4 - 1);
}
void flv_packet_mux(struct encoder_packet *packet, int32_t dts_offset,
uint8_t **output, size_t *size, bool is_header)
{
struct array_output_data data;
struct serializer s;
array_output_serializer_init(&s, &data);
if (packet->type == OBS_ENCODER_VIDEO)
flv_video(&s, dts_offset, packet, is_header);
else
flv_audio(&s, dts_offset, packet, is_header);
*output = data.bytes.array;
*size = data.bytes.num;
}
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