Abstract: A digital video recorder stores digital video streams having sequences of encoded frames that are predominantly non-keyframes. The digital video recorder synthesizes keyframes for the digital video stream by decoding the frames in sequence and occasionally capturing the state of the decoder as it decodes the frames. The decoder states are stored in a state index in association with the frames. During playback at normal or accelerated speeds, the digital video recorder is capable of random accelerated access of any frame in the digital video stream. A decoder state associated with the accessed frame is retrieved from the state index and used to begin decoding at or near the accessed frame. The decoder state initializes a playback decoder to the state that enables complete decoding and rendering of the accessed frame without having to decode multiple frames previous to the accessed frame, thereby minimizing time delays in playback.

Abstract: An implementation is described herein, which facilitates a fast channel change by receiving and decoding a unicast acquisition media stream that corresponds to a soon-to-be-requested target multicast media stream. It does this before requesting the target multicast media stream of the new channel. Once the transmission of the unicast stream is caught up with the multicast stream, this implementation splices from the unicast acquisition stream to the target multicast media stream.

Abstract: Aspects of the subject matter described herein relate to an offload provider. In aspects, an offload provider may provide a token that represents data. The offload provider may be expected to ensure that the data the token represents will not change while the token is valid. The offload provider may take actions to ensure the immutability of the data. The actions may be taken, for example, in conjunction with receiving an offload read and/or offload write, and/or in conjunction with receiving another write that, if allowed to proceed, would otherwise change the data represented by the token.

Abstract: Aspects of the subject matter described herein relate to a zero token. In aspects, a zero token may be used to represent one or more zeroes in an offload write command. A component receiving an offload write command with the zero token is free to write the zeroes in a variety of ways including, for example, changing data structures the component uses to represent the zeroes, issuing another command that writes zeroes, writing physical zeroes, and so forth. A component receiving an offload write command with the zero token does not need to verify that the zero token was obtained from a successful offload read or that the zero token is still valid. In response to an offload read request, a component may provide the zero token to represent all or a portion of the data associated with the offload read request.

Abstract: Improved hardware throughput can be achieved when a hardware device is saturated with IO jobs. Throughput can be estimated based on the quantifiable characteristics of incoming IO jobs. When IO jobs are received a time cost for each job can be estimated and stored in memory. The estimates can be used to calculate the total time cost of in-flight IO jobs and a determination can be made as to whether the hardware device is saturated based on completion times for IO jobs. Over time the time cost estimates for IO jobs can be revised based on a comparison between the estimated time cost for an IO job and the actual time cost for the IO job using aggregate IO job completion sequences.

Abstract: To comply with a policy for a computing device indicating that data written by the computing device to the storage volume after activation of the policy be encrypted, an encrypted chunks map is accessed. The encrypted chunks map identifies whether, for each chunk of sectors of a storage volume, the sectors in the chunk are unencrypted. In response to a request to write content to a sector, the encrypted chunks map is checked to determine whether a chunk that includes the sector is unencrypted. If the chunk that includes the sector is unencrypted, then the sectors in the chunk are encrypted, and the content is encrypted and written to the sector. If the chunk that includes the sector is encrypted or not in use, then the content is encrypted and written to the sector.

Abstract: Described are embodiments which allow token-based file operations. The client may request a special offload file operation that is formatted according to a file access protocol. The file operation may be an offload read operation or an offload write operation. In an offload read operation, the client requests that data be logically read from a stored file, or a portion thereof. In response, the file server provides a response that includes a token that represents the logically read data. In some embodiments, the file server may return a response with a token that represents less than all of the requested data if for some reason it cannot provide a token that represents all of the data. The token can then be used by the client in a subsequent offload write operation. In embodiments, the tokens represent immutable data that can be safely and securely used across servers and clients.

Abstract: Techniques are disclosed for managing the flow of IO jobs from a client to a hardware device such that resource starvation is reduced without significantly impacting throughput. Each flow can be assigned an amount of time that a hardware device can deplete completing IO jobs from the client. When the allocated amount of time is used IO jobs associated with the client can be stored in a queue until the client obtains more time.

Abstract: In an exemplary embodiment, a virtual disk file can be assigned an identifier and a virtual disk files that is dependent on the virtual disk file can include a copy of the identifier. In the instance that the virtual disk file is opened and data is modified that causes the contents of a virtual disk extent to change the identifier can be changed. If the virtual disk file and the dependent virtual disk file are used to instantiate a virtual disk the difference between identifiers can be detected, which is indicative of the fact that the virtual disk may be corrupted. Other techniques are described in the detailed description, claims, and figures that form a part of this document.

Abstract: Various aspects are disclosed herein for replacing the hardware backing the memory locations associated with a virtual machine with a backing mechanism. The backing mechanism may have the memory locations appear to contain data convenient to the driver in the virtual machine, typically containing what the hardware would have returned if the hardware had been read from. The data image being returned from the memory locations may travel with the virtual machine even if the virtual machine moves to a different physical machine that does not contain hardware equivalent to the hardware that was recently removed from the virtual machine.

Abstract: This document describes techniques for effecting a virtual disk. In an exemplary configuration, a virtual disk file can be associated with a log that acts as both a log and a check point record. When a log entry is generated, information that identifies the tail can be stored therein. This information can be used in the event that virtual disk file is improperly closed, i.e., a crash or power failure occurs, to discover a sequence of log entries to replay. In addition to the foregoing, other techniques are described in the claims, detailed description, and figures.

Abstract: This document describes techniques for storing virtual disk payload data. In an exemplary configuration, each virtual disk extent can be associated with state information that indicates whether the virtual disk extent is described by a virtual disk file. Under certain conditions the space used to describe a virtual disk extent can be reclaimed and state information can be used to determine how read and/or write operations directed to the virtual disk extent are handled. In addition to the foregoing, other techniques are described in the claims, figures, and detailed description of this document.

Abstract: Batching techniques are provided to maximize the throughput of a hardware device based on the saturation point of the hardware device. A balancer can determine the saturation point of the hardware device and determine the estimated time cost for IO jobs pending in the hardware device. A comparison can be made and if the estimated time cost total is lower than the saturation point one or more IO jobs can be sent to the hardware device.

Abstract: An entertainment system, having a capability to playback a stored digital video record that includes frames of video data received from a television broadcast system, approximates ranges of frames in a digital video record that are either commercials or non-commercials. The system also approximates frames that are either a beginning or an ending of a commercial or a non-commercial. The system then associates as a commercial two of the approximated frames that are a beginning or an ending of a commercial or a non-commercial and one or more of the approximated ranges there between until a predetermined percentage of the playback time of the digital video record is taken up by the associated commercials.

Abstract: Various aspects are disclosed herein for replacing the hardware backing the memory locations associated with a virtual machine with a backing mechanism. The backing mechanism may have the memory locations appear to contain data convenient to the driver in the virtual machine, typically containing what the hardware would have returned if the hardware had been read from. The data image being returned from the memory locations may travel with the virtual machine even if the virtual machine moves to a different physical machine that does not contain hardware equivalent to the hardware that was recently removed from the virtual machine.

Abstract: Aspects of the subject matter described herein relate to virtualization and offload reads and writes. In aspects, an offload read allows a requestor to obtain a token that represents data while an offload write allows the requestor to request that the data (or a part thereof) represented by a token be logically written. Offload reads and writes may be used to perform various actions for virtual environments.

Abstract: A method of agreeing on the utilization of at least one computer resource between two virtual machines includes sending a first resource request by a first virtual machine to a second virtual machine having computer resources to allocate to the first virtual machine. The second virtual machine responds by sending at least one available resource for use by the first virtual machine. The first virtual machine can select from the at least one available resource. Both the first and second virtual machines can then execute on the agreed resource utilization by the first virtual machine and begin using the resource. When conditions change, either the first virtual machine or the second virtual machine can request a renegotiation of the agreement to use computer resources.

Abstract: Techniques for configuring a commodity server to host virtual hard disks are disclosed herein. In an exemplary embodiment, a virtual hard disk file can be split into a plurality of differencing VHD files and one or more of the files can be downloaded to a virtualization host as it runs off the VHD files stored on the server. After the one or more VHD files are downloaded, the virtualization host can be configured to use the local copy instead of the copy on the commodity server. In addition to the foregoing, other techniques are described in the claims, the detailed description, and the figures.

Abstract: Techniques for configuring and operating a virtual desktop session are disclosed herein. In an exemplary embodiment, an inter-partition communication channel can be established between a virtualization platform and a virtual machine. The inter-partition communication channel can be used to configure a guest operating system to conduct virtual desktop sessions and manage running virtual desktop sessions. In addition to the foregoing, other techniques are described in the claims, the detailed description, and the figures.

Abstract: Aspects of the subject matter described herein relate to offload reads and writes. In aspects, a requestor that seeks to transfer data sends a request for a representation of the data. In response, the requestor receives one or more tokens that represent the data. The requestor may then provide one or more of these tokens to a component with a request to write data represented by the one or more tokens. In some exemplary applications, the component may use the one or more tokens to identify the data and may then read the data or logically write the data without additional interaction with the requestor. Tokens may be invalidated by request or based on other factors.