Audio encoder and decoder with program loudness and boundary metadata
Apparatus and methods for generating an encoded audio bitstream, including by including program loudness metadata and audio data in the bitstream, and optionally also program boundary metadata in at least one segment (e.g., frame) of the bitstream. Other aspects are apparatus and methods for decoding such a bitstream, e.g., including by performing adaptive loudness processing of the audio data of an audio program indicated by the bitstream, or authentication and/or validation of metadata and/or audio data of such an audio program. Another aspect is an audio processing unit (e.g., an encoder, decoder, or post-processor) configured (e.g., programmed) to perform any embodiment of the method or which includes a buffer memory which stores at least one frame of an audio bitstream generated in accordance with any embodiment of the method.
1. A non-transitory storage medium including at least one frame of an encoded audio bitstream, the at least one frame comprising:
a synchronization information section including a frame synchronization word;
a bitstream information section following the synchronization information section, the bitstream information including audio metadata;
an additional bitstream information section located at an end of the bitstream information section;
up to six blocks of audio data following the bitstream information section;
an auxiliary information section following the six blocks of audio data;
an error correction word following the auxiliary information section; and
one or more skip fields containing any unused space remaining in the at least one frame,
wherein the at least one frame includes a metadata container located in a reserved data space selected from the group consisting of the one or more skip fields, the additional bitstream information section, the auxiliary information section, or a combination thereof,
wherein the metadata container includes:
a header identifying a start of the metadata container, the header including a syncword followed by a length field specifying a length of the metadata container,
a format version field following the header, the format version field specifying a format version of the metadata container,
one or more metadata payloads following the format version field, each metadata payload including an identifier uniquely identifying the metadata payload followed by metadata of the metadata payload, at least one metadata payload includes a program loudness payload, and the loudness payload includes a loudness regulation type field, the loudness regulation type field consisting of a 4-bit field indicating which loudness regulation standard was used to calculate a program loudness associated with the audio data, and
protection data following the one or more metadata payloads, the protection data for authenticating or validating the metadata container or the one or more metadata payloads within the metadata container.
2. The non-transitory storage medium of claim 1 wherein the syncword is a 16 bit field having a value of 0x5838.
3. The non-transitory storage medium of claim 1 wherein the one or more metadata payloads includes a program loudness payload, and the loudness payload includes a dialogue channel field, the dialogue channel field consisting of a 3-bit field indicating whether a left, right or center channel of the audio data contains spoken dialogue.
4. The non-transitory storage medium of claim 1 wherein the one or more metadata payloads includes a program loudness payload, wherein the program loudness payload includes a loudness correction type, the loudness correction type consisting of a 1-bit field indicating whether the audio data was corrected with an infinite look-ahead or file-based loudness correction process.
5. The non-transitory storage medium of claim 1 wherein the storage medium represents an input buffer of an audio decoder.
6. An audio decoder comprising the non-transitory computer readable medium of claim 1 .
7. An audio decoder for decoding an encoded audio bitstream, the audio decoder comprising:
a buffer memory for storing at least one frame of an encoded audio bitstream;
an audio decoder coupled to the buffer memory for decoding the audio data; and
a parser coupled to or integrated with the audio decoder for parsing the encoded audio bitstream,
wherein the at least one frame comprises:
a synchronization information section including a frame synchronization word;
a bitstream information section following the synchronization information section, the bitstream information including audio metadata;
an additional bitstream information section located at an end of the bitstream information section;
up to six blocks of audio data following the bitstream information section;
an auxiliary information section following the six blocks of audio data;
an error correction word following the auxiliary information section; and
one or more skip fields containing any unused space remaining in the at least one frame,
wherein the at least one frame includes a metadata container located in a reserved data space selected from the group consisting of the one or more skip fields, the additional bitstream information section, the auxiliary information section, or a combination thereof,
wherein the metadata container includes:
a header identifying a start of the metadata container, the header including a syncword followed by a length field specifying a length of the metadata container,
a format version field following the header, the format version field specifying a format version of the metadata container,
one or more metadata payloads following the format version field, each metadata payload including an identifier uniquely identifying the metadata payload followed by metadata of the metadata payload, at least one of the metadata payloads includes a program loudness payload, and the loudness payload includes a loudness regulation type field, the loudness regulation type field consisting of a 4-bit field indicating which loudness regulation standard was used to calculate a program loudness associated with the audio data, and
protection data following the one or more metadata payloads, the protection data for authenticating or validating the metadata container or the one or more metadata payloads within the metadata container.