Systems and methods for implementing cross-fading, interstitials and other effects downstream
Systems and methods are presented for cross-fading (or other multiple clip processing) of information streams on a user or client device, such as a telephone, tablet, computer or MP3 player, or any consumer device with audio playback. Multiple clip processing can be accomplished at a client end according to directions sent from a service provider that specify a combination of (i) the clips involved; (ii) the device on which the cross-fade or other processing is to occur and its parameters; and (iii) the service provider system. For example, a consumer device with only one decoder, can utilize that decoder (typically hardware) to decompress one or more elements that are involved in a cross-fade at faster than real time, thus pre-fetching the next element(s) to be played in the cross-fade at the end of the currently being played element. The next elements(s) can, for example, be stored in an input buffer, then decoded and stored in a decoded sample buffer, all prior to the required presentation time of the multiple element effect. At the requisite time, a client device component can access the respective samples of the decoded audio clips as it performs the cross-fade, mix or other effect. Such exemplary embodiments use a single decoder and thus do not require synchronized simultaneous decodes.
1. A method for implementing multiple element effects on audio packets on a client device having a single hardware decoder, comprising:
downloading on a client device compressed audio clips to be used in a multiple element effect;
storing the compressed audio in an input buffer;
sequentially decoding at least one of said clips at a rate that is faster than real time;
storing the decoded clips in separate portions of a decoded sample buffer; and
accessing respective samples of the decoded clips from the decoded sample buffer while performing the effect.
2. The method of claim 1 , wherein said multiple element effect is one of a linear cross-fade, nonlinear cross-fade, mix, voice over, voice over with sound effect, and multiple sound effect.
3. The method of claim 1 , wherein at least one of:
(i) the multiple element effect is a clip overlay to a cross-fade between two clips, and the second clip is decoded at a faster than real-time rate; and
(ii) the multiple element effect is a clip overlay to a cross-fade between two clips, the second clip is decoded at a faster than real-time rate, and the clip overlay is downloaded in an uncompressed format.
4. The method of claim 1 , further comprising taking the signal levels of the decoded audio clips and generating a new signal level for a resulting frame based on the blend rate of the multiple element effect.
5. A method for faster than real time cross-fading of audio packets on a device where access to a decoded audio buffer is unavailable, comprising:
(a) decoding a first audio clip through a first decoder;
(b) testing if the current frame is part of an intro;
if it is not, playing the frame at 100% volume;
if it is, determining if a second decoder is running;
if a second decoder is running, then incrementing the first decoder's volume and decrementing the second decoder's volume;
if there is not a second decoder running, then maintaining the first decoder's volume at 100%.
6. The method of claim 5 , further comprising:
determining if the current frame is the last frame in the first audio clip;
if yes, stop decoding the first audio clip; and
if no, obtain a next frame of the first audio clip and repeat (b).
7. A method for faster than real time cross fading of audio packets on a device where access to un-encoded audio is unavailable, comprising:
(a) decoding a first audio clip through a first decoder;
(b) testing if the current frame sent to the decoder is part of an outro;
if it is not, playing the frame at 100% volume;
if it is, determining if a second decoder is running;
if a second decoder is running, then decrement the volume of the first decoder and increment the volume of the second decoder; and
if there is not a second decoder running, then maintaining the first decoder's volume at 100%.
8. A method for implementing multiple element effects on audio packets on a client device having a single hardware decoder, comprising:
downloading compressed and uncompressed audio clips to be used in the multiple element effect;
storing the audio in an input buffer;
sequentially decoding at least one of said compressed clips at a rate that is faster than real time;
storing the decoded clips in separate portions of a decoded sample buffer;
accessing respective samples of the decoded clips from the decoded sample buffer and uncompressed clips from the input buffer while performing the effect.
9. The method of claim 8 , wherein the downloaded uncompressed elements are short clips used during crossfades, mixes and blends.