實際上,我已經能夠生成時間戳,並且可以使用一些過濾器(複用器),但由於我想能夠使用GDCL MP4 Multiplexer Filter
,我想討論一下計算採樣時間值的方法。如何在RTSP源過濾器中生成樣本時間戳?
奇怪的是,如果我把Smart Tee Filter
放在我的RTSP Source Filter
和GDCL MP4 Multiplexer Filter
之間,一切似乎都有效。我能夠正確捕捉視頻流。但沒有Smart Tee Filter
,我仍然能夠捕捉視頻,但這次與定期毛刺。據我所知,Smart Tee Filter
除了提供雙輸出引腳,一個帶有時間戳(捕獲引腳)和一個沒有時間戳(預覽引腳)並且兩個引腳共享相同的流緩衝區之外,沒有多大作用。所以,我想到的東西是不知何故Smart Tee Filter
重組像時間戳的東西。但是如果我不生成時間戳,Smart Tee Filter
也不會生成這些值。我目前的猜測是,我正確計算了幀的開始時間,但是幀的停止時間不正確,並且Smart Tee Filter
正在重新計算幀停止時間(這只是當然的猜測)。
我用來計算開始和停止時間,如下面的公式。
startTime = now
timeDelta = now - previousFrame
endTime = startTime + timeDelta
這不是確切的公式,但它是接近的東西。結果如下。
Media Time/Time: 0-1 0-0
Media Time/Time: 1-2 500028-1000056
Media Time/Time: 2-3 930053-1360078
Media Time/Time: 3-4 1610092-2290131
Media Time/Time: 4-5 2200126-2790160
Media Time/Time: 5-6 2900166-3600206
Media Time/Time: 6-7 3500200-4100234
Media Time/Time: 7-8 4240242-4980284
Media Time/Time: 8-9 4720270-5200298
Media Time/Time: 9-10 5350306-5980342
Media Time/Time: 10-11 5980342-6610378
Media Time/Time: 11-12 6610378-7240414
Media Time/Time: 12-13 7250414-7890450
Media Time/Time: 13-14 7880450-8510486
Media Time/Time: 14-15 8510486-9140522
Media Time/Time: 15-16 9140522-9770558
Media Time/Time: 16-17 9780559-10420596
Media Time/Time: 17-18 10410595-11040631
Media Time/Time: 18-19 11040631-11670667
Media Time/Time: 19-20 11680668-12320705
Media Time/Time: 20-21 12310704-12940740
Media Time/Time: 21-22 12940740-13570776
Media Time/Time: 22-23 13600778-14260816
Media Time/Time: 23-24 14220813-14840848
Media Time/Time: 24-25 14840849-15460885
Media Time/Time: 25-26 15480885-16120921
Media Time/Time: 26-27 16110921-16740957
Media Time/Time: 27-28 16740957-17370993
Media Time/Time: 28-29 17380994-18021031
Media Time/Time: 29-30 18011030-18641066
Media Time/Time: 30-31 18631065-19251100
這些都是媒體的時間和由SetMediaTime()和SETTIME()方法來設置時間值(無論是在啓停格式)。我看到的問題是一些開始/結束時間在連續幀中重疊。當然這是由抖動因素等引起的。如果我根據前一幀計算時間增量,並且如果下一幀比預期更早到達,則會發生重疊。所以,我在代碼中做了一些改動。我的最終代碼如下所示。
_FILETIME fileTime;
GetSystemTimeAsFileTime(&fileTime);
now = ((((__int64)fileTime.dwHighDateTime << 32) + fileTime.dwLowDateTime) - streamReader->rtpProtocolHandler->m_iReferenceTime);
timeDelta = now - m_iFrameTimePrevious;
m_iFrameTime = max(now, m_iFrameTime);
m_iFrameTimePrevious = m_iFrameTime;
REFERENCE_TIME rtStart = m_iFrameTime;
REFERENCE_TIME rtStop;
if(timeDelta > 0) {
m_iFrameTime += timeDelta;
rtStop = m_iFrameTime;
} else {
rtStop = rtStart;
}
pSample->SetTime(&rtStart, &rtStop);
pSample->SetMediaTime(&m_iMediaTime, &(++m_iMediaTime));
和結果是這樣的:
Media Time/Time: 0-1 0-0
Media Time/Time: 1-2 470027-940054
Media Time/Time: 2-3 940054-1380079
Media Time/Time: 3-4 1580091-2220128
Media Time/Time: 4-5 2220128-2810161
Media Time/Time: 5-6 2870164-3520200
Media Time/Time: 6-7 3520200-4110234
Media Time/Time: 7-8 4170239-4820278
Media Time/Time: 8-9 4820278-5420312
Media Time/Time: 9-10 5470313-6120348
Media Time/Time: 10-11 6120348-6720382
Media Time/Time: 11-12 6770387-7420426
Media Time/Time: 12-13 7420426-8060463
Media Time/Time: 13-14 8060463-8630494
Media Time/Time: 14-15 8630494-9140521
Media Time/Time: 15-16 9260530-9890566
Media Time/Time: 16-17 9890566-10490600
Media Time/Time: 17-18 10560604-11230642
Media Time/Time: 18-19 11230642-11840677
Media Time/Time: 19-20 11860679-12490716
Media Time/Time: 20-21 12490716-13090750
Media Time/Time: 21-22 13170754-13850792
Media Time/Time: 22-23 13850792-14450826
Media Time/Time: 23-24 14460827-15070862
Media Time/Time: 24-25 15070862-15680897
Media Time/Time: 25-26 15760902-16450942
Media Time/Time: 26-27 16450942-17060977
Media Time/Time: 27-28 17100978-17751014
Media Time/Time: 28-29 17751014-18171038
Media Time/Time: 29-30 18171040-18591066
Media Time/Time: 30-31 18771074-19371108
沒有重疊,但這次所有的故障仍然存在。我究竟做錯了什麼?
請記住,我的源過濾器可以與其他mp4複用器配合使用,如果我將Smart Tee過濾器放在中間位置,它也可以與GDCL MP4複用器配合使用。