Background technology
For reappearing for example with DTV, digital broadcasters, even also the method for the Media Stream relevant with internet isIt is known.IP radios with Internet connection are known.
Although DTV and digital broadcasters are using the transmission rate limited, but transmission rate is using internetWhen be variable.When this is especially for mobile phone mobile link or in vehicle.
On the one hand people use depending on possible transmission speed and initially set, flexible transfer rate or bitRate, on the other hand uses the buffer (English as intermediate store：Buffer), so as to postpone so-called stream in short time.Thus prevent packet from not reaching when mobile communication is connected, or must ask again.For example between after loading buffer notRealize disconnectedly and listen song.Therefore, the buffer ensures not interrupting the reproduction in the time of the restriction depending on buffer sizes.
But because insecure quality of connection needs several seconds, very big buffer in vehicle.It is known thatEstimate at least 5 seconds by standard for example in Tuneln in IP radios.But as a result, in calling IP sender with broadcastingPass through about 8-12 seconds between putting.But if being unsatisfied with the program and selecting next sender, then must resume waiting for 8-12 seconds.Therefore, the website of " thoroughly scanning " for example in frequency modulation broadcasting is impossible, and substantially infringement and IP radiosExchange and the receiving to IP radios.
In order to realize that some are remedied, it is possible to reduce buffer, quickly to hear broadcast transmission person.But in being due to vehicleInsecure network connection to reappear interrupts very fast, and this is equally undesirable.The interruption be perceived as shut down orMusic or voice interruption and cause maximum interference.
A kind of method for being used to create Streaming Media and one kind are used for transport stream as known to the A1 of DE 10 2,006 016 549The method of media.Application such as the Internet radio can be realized by the video flowing of internet.In gradual stream, in order toTransmitting data needs common http-server.Need to buffer received data for the player of reproduction, and when it is slowRush device to be filled when the percentage of determination, automatically begin to the reproduction.
The content of the invention
The task of the present invention is, improves the method for being previously mentioned type so that on the one hand avoid in switching IP radiosSender when it is too long of wait, but on the other hand again eliminate reappear interrupt risk.
The task is solved by the method with the feature illustrated in claim 1.
The present invention realizes that the stream postponed less in insecure network reappears.
The present invention solves high latency and the problem of music is interrupted by simple mode.According to few delay of the present inventionStream reappear and be particularly suitable for use in insecure network, and the mobile subscriber for contributing to quantity to be skyrocketed through, such as smart mobile phoneUser, vehicle user etc..
The present invention can be close to without delay or lingeringly next in UMTS or LTE realization reproductions less than 1 secondSender, while maintaining the buffer for connection interference.
It is an advantage of the invention that：
First, it is switched fast between sender, such as in frequency modulation broadcasting,
Second, for variable, definable the buffer for ensuring to reappear in connection interference,
3rd, the variable method for fill buffer is formed, thus, it is possible to need slightly to adjust according to userMass loss, or mass loss be not almost perceived,
4th, for the applicability of any stream, the especially video and/or audio (such as IP) with backward channel,Wherein easily realized in the applicability of server end (sender) and client (recipient), and
5th, on the receive side using when, it is not necessary to change existing server.
The present invention be allowed in insecure network by automatic adaptation cushion with variable reproduction speed less lingeringlyReappear the method for stream.
The present invention is based on following thought, i.e., relatively large buffering is not filled with when method starts, when this causes the wait of lengthBetween just reappear, but begin to reappear after the less minimal buffering of filling is reached, but this is slower than true output, thus byGradually build the Target buffer time.
The present invention is based on following thought, even if with the buffer with variable memory size, so that for reappearingWhen the method for Media Stream starts, minimal buffering is filled before Media Stream is reappeared, wherein just being opened after filling minimal buffering is reachedStarting weight shows.
Minimal buffering is limited in the following manner, i.e., be embodied as the memory size of minimal buffering so that memory existsBecome full in less than 1 second.That is, the weight of audio signal is carried out now less than in 1 second.
The minimal buffering can be virtual software buffering.Alternate embodiments can be physical storage areas.
Other favourable technical schemes of the present invention are represented in the dependent claims.
Provided in the favourable expansion scheme of the driver according to the present invention, buffer is more slowly more defeated than real-playbackGo out, wherein change in pitch is compensated by carrying out or performing pitch compensation, to adjust the pitch of real audio reproduction.Because simulation change in pitch can be caused or can cause " reproduction of more bass " by more slowly playing flow data, phase must be passed throughThe pitch compensation method answered by commercially available algorithm to compensate pitch again poor so that pitch is suitableIn original value.The quality and frequency of resampling are determined by sound quality or its loss and are substantially dependent upon operational performance.Pitch regulation is for example found in guitar effect device or DJ equipments and can easily applied herein.
A kind of linear buffering strategy is described in another favourable technical scheme of the present invention.Reaching minimal bufferingAfterwards, with the time linearly fill buffer and improve until full buffer sizes, wherein at least can temporarily reduce pitchChange or extensibility.It can realize and easily realize single linear slope.Different, preferably two kinds slopes are preferably used.Linear buffer strategy with intermittent extension is also advantageous.
The especially advantageous expansion scheme of the present invention is characterised by, it is proposed that a kind of buffering plan with adaptive strain stretchSlightly.Its increment substantially exponentially mode reduces, so that the increment is intended to zero at the end of filling process.
Embodiment
Fig. 1 shows the schematic diagram that the IP streams converted with website reappear, and website conversion has according to prior art touchesSend out time point and recurring temporal point.
S1 and S2 represent first-class S1 and second S2, and wherein NSL represents the input or order E1 or use in userThe network and system latency time (delay) existed after the request of family.Tx and Rx represent sender and recipients.Line SSt represents to sendStream, t1 represents the buffer time of 5 to 10 seconds.Set sender can not be heard within the time.User has to wait for.Accompanying drawingMark P represents to reappear or heard that reference NP represents not reappear.Audio reproduction is carried out after t1, it is by SPM1(Start Playing Music, commence play out music) is represented.Hereafter, user hears sound at such as 3 seconds or during t2It is happy.If user does not like the music, it is searched for again through order E2 operation senders, so that after SSt or NSLThe stand-by period or buffer time again of 5 to 10 seconds, listened again in time t3 or in SPM2 (commencing play out music)To another sender.
Therefore, Fig. 1 is shown in IP auto radios because long stand-by period t1, t2 do not obtain the fortune of satisfactionOK.
It is due in vehicle to hear broadcast transmission person more quickly although buffering or t1 and t2 can be reducedIn insecure network connection and rapidly interrupt reproduction, this is equally interfered.
Fig. 2 shows the schematic diagram similar to Fig. 1, but has the application of the method according to the invention.Can beSender is heard after the time t1 of about 0.4 second.Reproduction or buffering with the automatic adaptation cushion by stretching are set hereinStrategy.
As shown in Fig. 2 being realized by the method according to the invention under identical use condition on until media reappearTime delay improved time response.
Provided in the method according to Fig. 2, be not the filling that buffer is built when starting to reappear in the receiver, butAccording to present invention provide that starting to reappear after minimal buffering is reached.Reproduction output is slower than actual, so as to gradually build up targetBuffer time.Change in pitch is compensated by pitch compensation method, so that pitch is equivalent to original value.
Fig. 3 shows the first variations of the method according to Fig. 2.It follows linear buffering strategy.Fig. 2 is schematicallyShow the fill level in each stage buffer.
Represent herein：
Bmax：Maximum cushioning
Bmin：Minimal buffering
tL：System latency time (t delay)
tP：Buffer is pre-charged with the time (t buffers are pre-filled)
tF：Buffer refilling time (filling of t buffers)
BF：Full buffer (buffer full)
UR：The stream 1 of user's request
SW：Slow down and start to reappear
E1：First event starts to be pre-charged with buffer about 0.3 second with maximum speed, wherein without soundReappear.
E2：Second event is reappeared, fill buffer with the speed of reduction, until it is expired.
E3：3rd event or buffer full, start to reappear with normal speed.
User is asked to flow to server, and the stream is prepared after certain stand-by period tL, and waiting time is due to netNetwork (being for example 100ms in case of umts) and system are formed.Fill buffer (referring to the E1) since the preparation, certainly onlyExtremely few time, it is roughly equivalent to twice of stand-by period (about 300ms in case of umts) to three times.At thisBetween after, with the output speed of reduction start reappear.Buffer is gradually filled to its desired value, (is joined preferably after 5 secondsSee E3).As long as buffer is filled, then the stream is reappeared with raw velocity.
The computational methods of the rate of deceleration (extensibility) are as follows：
Extensibility=(tMaximum cushioning-tMinimal buffering)/tBuffer is filled
That is, if buffer to be building up to the desired value of 5 seconds with the initial buffer of 0.3 second in 47 seconds, itsExtensibility equivalent to 10%.
Time for fill buffer is obtained by following formula：
tBuffer is filled=(tMaximum cushioning–tMinimal buffering)/extensibility
If reducing extensibility, the reproduction is further maintained original value, be then increased up and fill up bufferTime, and therefore also increase the danger shut down in insecure network.Therefore, the parameter always represents that sound is deteriorated with stoppingThe compromise of machine risk.In addition, being hard from filling stage (E2 to E3) to the transitional representation in the stage (since E3) of normal reproductionTransition, should be especially perceptible in music as hard as crossing.Therefore meaningful using following methods, it not only causes this to delayRush device rapidly but be filled with escaping detection, and more mildly form the transition to raw velocity.
Therefore, the second variations are effective, wherein following the linear buffer strategy with intermittent extension.
Fig. 4 essentially show foregoing method, but with extension, wherein using media interval (in videoIt is no sound in audio for black picture), to extend media interval, and it is slow with maximal rate filling within the timeRush device.
It is expressed as herein：
QSD：Detection stream (the Jing Yin point in the stream detected)
QSE：Stretching stream (the Jing Yin stream in the stream extended)
SPS：Slow down reproduction (slow down and commence play out)
tq：Quiescent time (tquite)
tqe：Stretch (tqe)
E1：First event or with maximum speed about 0.3 second, start to be pre-charged with buffer voiceless sound.
E2：Second event is reappeared with the speed of reduction
E3：3rd event or resting stage, without sound, with maximum speed fill buffer.
E4：4th event is reappeared, fill buffer with the speed of reduction, until it is expired.
E5：First event or buffer full, start to reappear with normal speed.
Until E3, the process is all as depicted in fig. 3.But interval (such as without sound) is recognized in the position and sameSample, which reappears, to be stopped.The interval shows as the several times of original interval for a user, but is no more than maximum (such as 3Second).It therefore, it can further fill up buffer in real time, and user will not substantially be aware of this point, or user does not have completelyHave and realize.
The another variant scheme of this method follows the buffering strategy with adaptive strain stretch.
Fig. 5 shows another extension, has peak when wherein this is stretching in beginning and in the process that buffer is filledIt is lasting to reduce.In the transition to primary flow, the difference of reproduction speed is so small, so that user does not realize.
The E1 to E3 that E1 to E3 in Fig. 5 corresponds in Fig. 3.
That is, Fig. 5 shows a kind of buffering strategy with adaptive strain stretch.In of short duration linear buffer, (E1 is extremelyE2 after), since E2 reappeared with maximum tension.But the stretching reduces always, thus to primary flow (E3) transition notThere is the noticeable speed difference arrived again.
Foregoing method can be used alone or can also be combined with each other.
The above method can be combined with wireless IP streams (video and audio), especially by UMTS and LTE, with can be described asThe stream of PBS is combined.What is cherished a special interest herein is audio stream, because IP radios wide-scale distribution and having for a long timeThere is potential to replace frequency modulation broadcasting.Popular IP radio services APP such as Tuneln for example has in application shop to be exceeded50000000 download.The APP is provided by most notable vehicular manufacturer simultaneously.IP radio senders (are for example equally based onShoutcast all suppliers of front end) can be the potential user of the technology.Therefore in addition to smart mobile phone APP itsIt can be proprietary solution in vehicle, for example, be built directly in head unit (Head Unit).
IP radios for wireless application are significantly improved based on the realization of already present technology by described methodExperience, its mode is postponed by such as being reduced when sender switches in peer-level when current FM is received, but it is protectedStay the advantage for being related to digital broadcasting quality.This is especially probably the key module for breaking through IP radios in vehicle.
Reference numerals list
Buffer full BF
The events of E1 first
E2 second events
The events of E3 the 3rd
NP does not reappear
NSL networks and system latency time
P reappears or listened
QSD detection streams
QSE stretching streams
S1 is first-class
S2 seconds
SPM1 audio reproductions
SPS slows down reproduction
SSt sends stream
SW, which slows down, to be started to reappear
UR user's request streams