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avformat/fifo: add timeshift option to delay output

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Signed-off-by: Marton Balint <cus@passwd.hu>
pull/340/head
Marton Balint 5 years ago
parent cdac618c9b
commit 81975cd24b
3 changed files with 64 additions and 2 deletions
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  1. 5
      doc/muxers.texi
  2. 59
      libavformat/fifo.c
  3. 2
      libavformat/version.h

5
doc/muxers.texi
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@ -2275,6 +2275,11 @@ certain (usually permanent) errors the recovery is not attempted even when
Specify whether to wait for the keyframe after recovering from
queue overflow or failure. This option is set to 0 (false) by default.
@item timeshift @var{duration}
Buffer the specified amount of packets and delay writing the output. Note that
@var{queue_size} must be big enough to store the packets for timeshift. At the
end of the input the fifo buffer is flushed at realtime speed.
@end table
@subsection Examples

59
libavformat/fifo.c
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@ -19,6 +19,8 @@
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdatomic.h>
#include "libavutil/avassert.h"
#include "libavutil/opt.h"
#include "libavutil/time.h"
@ -77,6 +79,9 @@ typedef struct FifoContext {
/* Value > 0 signals queue overflow */
volatile uint8_t overflow_flag;
atomic_int_least64_t queue_duration;
int64_t last_sent_dts;
int64_t timeshift;
} FifoContext;
typedef struct FifoThreadContext {
@ -98,9 +103,12 @@ typedef struct FifoThreadContext {
* so finalization by calling write_trailer and ff_io_close must be done
* before exiting / reinitialization of underlying muxer */
uint8_t header_written;
int64_t last_received_dts;
} FifoThreadContext;
typedef enum FifoMessageType {
FIFO_NOOP,
FIFO_WRITE_HEADER,
FIFO_WRITE_PACKET,
FIFO_FLUSH_OUTPUT
@ -159,6 +167,15 @@ static int fifo_thread_flush_output(FifoThreadContext *ctx)
return av_write_frame(avf2, NULL);
}
static int64_t next_duration(AVFormatContext *avf, AVPacket *pkt, int64_t *last_dts)
{
AVStream *st = avf->streams[pkt->stream_index];
int64_t dts = av_rescale_q(pkt->dts, st->time_base, AV_TIME_BASE_Q);
int64_t duration = (*last_dts == AV_NOPTS_VALUE ? 0 : dts - *last_dts);
*last_dts = dts;
return duration;
}
static int fifo_thread_write_packet(FifoThreadContext *ctx, AVPacket *pkt)
{
AVFormatContext *avf = ctx->avf;
@ -167,6 +184,9 @@ static int fifo_thread_write_packet(FifoThreadContext *ctx, AVPacket *pkt)
AVRational src_tb, dst_tb;
int ret, s_idx;
if (fifo->timeshift && pkt->dts != AV_NOPTS_VALUE)
atomic_fetch_sub_explicit(&fifo->queue_duration, next_duration(avf, pkt, &ctx->last_received_dts), memory_order_relaxed);
if (ctx->drop_until_keyframe) {
if (pkt->flags & AV_PKT_FLAG_KEY) {
ctx->drop_until_keyframe = 0;
@ -209,6 +229,9 @@ static int fifo_thread_dispatch_message(FifoThreadContext *ctx, FifoMessage *msg
{
int ret = AVERROR(EINVAL);
if (msg->type == FIFO_NOOP)
return 0;
if (!ctx->header_written) {
ret = fifo_thread_write_header(ctx);
if (ret < 0)
@ -390,12 +413,13 @@ static void *fifo_consumer_thread(void *data)
AVFormatContext *avf = data;
FifoContext *fifo = avf->priv_data;
AVThreadMessageQueue *queue = fifo->queue;
FifoMessage msg = {FIFO_WRITE_HEADER, {0}};
FifoMessage msg = {fifo->timeshift ? FIFO_NOOP : FIFO_WRITE_HEADER, {0}};
int ret;
FifoThreadContext fifo_thread_ctx;
memset(&fifo_thread_ctx, 0, sizeof(FifoThreadContext));
fifo_thread_ctx.avf = avf;
fifo_thread_ctx.last_received_dts = AV_NOPTS_VALUE;
while (1) {
uint8_t just_flushed = 0;
@ -429,6 +453,10 @@ static void *fifo_consumer_thread(void *data)
if (just_flushed)
av_log(avf, AV_LOG_INFO, "FIFO queue flushed\n");
if (fifo->timeshift)
while (atomic_load_explicit(&fifo->queue_duration, memory_order_relaxed) < fifo->timeshift)
av_usleep(10000);
ret = av_thread_message_queue_recv(queue, &msg, 0);
if (ret < 0) {
av_thread_message_queue_set_err_send(queue, ret);
@ -488,6 +516,8 @@ static int fifo_init(AVFormatContext *avf)
" only when drop_pkts_on_overflow is also turned on\n");
return AVERROR(EINVAL);
}
atomic_init(&fifo->queue_duration, 0);
fifo->last_sent_dts = AV_NOPTS_VALUE;
oformat = av_guess_format(fifo->format, avf->url, NULL);
if (!oformat) {
@ -563,6 +593,9 @@ static int fifo_write_packet(AVFormatContext *avf, AVPacket *pkt)
goto fail;
}
if (fifo->timeshift && pkt->dts != AV_NOPTS_VALUE)
atomic_fetch_add_explicit(&fifo->queue_duration, next_duration(avf, pkt, &fifo->last_sent_dts), memory_order_relaxed);
return ret;
fail:
if (pkt)
@ -576,6 +609,27 @@ static int fifo_write_trailer(AVFormatContext *avf)
int ret;
av_thread_message_queue_set_err_recv(fifo->queue, AVERROR_EOF);
if (fifo->timeshift) {
int64_t now = av_gettime_relative();
int64_t elapsed = 0;
FifoMessage msg = {FIFO_NOOP};
do {
int64_t delay = av_gettime_relative() - now;
if (delay < 0) { // Discontinuity?
delay = 10000;
now = av_gettime_relative();
} else {
now += delay;
}
atomic_fetch_add_explicit(&fifo->queue_duration, delay, memory_order_relaxed);
elapsed += delay;
if (elapsed > fifo->timeshift)
break;
av_usleep(10000);
ret = av_thread_message_queue_send(fifo->queue, &msg, AV_THREAD_MESSAGE_NONBLOCK);
} while (ret >= 0 || ret == AVERROR(EAGAIN));
atomic_store(&fifo->queue_duration, INT64_MAX);
}
ret = pthread_join(fifo->writer_thread, NULL);
if (ret < 0) {
@ -630,6 +684,9 @@ static const AVOption options[] = {
{"recover_any_error", "Attempt recovery regardless of type of the error", OFFSET(recover_any_error),
AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM},
{"timeshift", "Delay fifo output", OFFSET(timeshift),
AV_OPT_TYPE_DURATION, {.i64 = 0}, 0, INT64_MAX, AV_OPT_FLAG_ENCODING_PARAM},
{NULL},
};

2
libavformat/version.h
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@ -33,7 +33,7 @@
// Also please add any ticket numbers that you believe might be affected here
#define LIBAVFORMAT_VERSION_MAJOR 58
#define LIBAVFORMAT_VERSION_MINOR 46
#define LIBAVFORMAT_VERSION_MICRO 100
#define LIBAVFORMAT_VERSION_MICRO 101
#define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
LIBAVFORMAT_VERSION_MINOR, \

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