Metadata transcoding

A method for generating an encoded bitstream comprising a content frame and an associated metadata frame;

• wherein the content frame is indicative of a signal encoded according to a first codec system;
• wherein the method comprises
• generating a block of metadata;
• inserting the block of metadata into the metadata frame;
• selecting a secure key from a plurality of pre-determined secure keys;
• wherein a first key of the plurality of pre-determined secure keys provides a first level of trust, and a second key of the plurality of pre-determined secure keys provides a second level of trust that is different from the first level;
• wherein the first key is a highly secure key known to only to a first set of entities;
• wherein the second key is a moderately secure key known to a second set of entities which includes the first set of entities;
• generating a cryptographic value based at least on the content frame, on the associated metadata frame and on the selected secure key;
• and
• inserting the generated cryptographic value into the metadata frame.

A decoding device, comprising one or more hardware elements, configured to receive an encoded bitstream comprising a content frame and an associated metadata frame;

• wherein the content frame is indicative of a signal encoded according to a first codec system;
• wherein the decoding device is configured to
• extract a cryptographic value from the metadata frame;
• determine a secure key from a plurality of pre-determined secure keys;
• wherein a first key of the plurality of pre-determined secure keys provides a first level of trust, and the second key of the plurality of secure keys provides a second level of trust that is different from the first level;
• wherein the first key is a highly secure key known to only to a first set of entities;
• wherein the second key is a moderately secure key known to a second set of entities which includes the first set of entities;
• generate a verification cryptographic value based at least on the content frame, on the associated metadata frame and on the determined secure key;
• and
• compare the extracted cryptographic value and the verification cryptographic value to determine whether the received encoded bitstream can be trusted.

A method for determining a level of trust of a received encoded bitstream comprising a content frame and an associated metadata frame;

• wherein the content frame is indicative of a signal encoded according to a first codec system;
• wherein the method comprises
• extracting a cryptographic value from the metadata frame;
• determining a secure key from a plurality of pre-determined secure keys;
• wherein a first key of the plurality of pre-determined secure keys provides a first level of trust, and a second key of the plurality of pre-determined secure keys provides a second level of trust that is different from the first level;
• wherein the first key is a highly secure key known to only to a first set of entities;
• wherein the second key is a moderately secure key known to a second set of entities which includes the first set of entities;
• generating a verification cryptographic value based at least on the content frame, on the associated metadata frame and on the determined secure key;
• and
• comparing the extracted cryptographic value and the verification cryptographic value to determine whether the received encoded bitstream can be trusted in accordance to the level of trust of the determined secure key.

A transcoding device, comprising one or more hardware elements, configured to transcode an inbound bitstream comprising an inbound content frame and an associated inbound metadata frame into an outbound bitstream;

• wherein the inbound bitstream is indicative of a set of samples of a signal;
• wherein the transcoding device comprises
• a decoder configured to
• convert the inbound content frame into a set of decoded Pulse Code Modulated, referred to as PCM, samples of the signal;
• extract metadata from the inbound metadata frame;
• identify an inbound block of metadata from the inbound metadata frame;
• wherein the inbound block of metadata is associated with an inbound descriptor indicative of one or more properties of metadata comprised within the inbound block of metadata, wherein the one or more properties comprise a PCM processing parameter indicative of whether or not the metadata of the inbound block is to be discarded by an encoder, subject to a modification of the set of PCM samples and/or the extracted metadata;
• and
• generate a signature value for the set of decoded PCM samples and the extracted metadata, using a decoder secure key;
• and
• the encoder configured to
• receive a set of PCM samples and associated metadata;
• receive a signature value;
• verify whether the received signature value is valid for the received set of PCM samples and associated metadata, using an encoder secure key;
• and
• generate an outbound content frame of the outbound bitstream from the received set of PCM samples and generate an associated outbound metadata frame of the outbound bitstream from the inbound metadata frame based on the inbound descriptor, if the received signature is valid.

A method for transcoding an inbound bitstream comprising an inbound content frame and an associated inbound metadata frame into an outbound bitstream;

• wherein the inbound bitstream is indicative of a set of samples of a signal;
• the method comprising,
• at a decoder,
• converting the inbound content frame into a set of decoded Pulse Code Modulated, referred to as PCM, samples of the signal;
• extracting metadata from the inbound metadata frame;
• identifying an inbound block of metadata from the inbound metadata frame;
• wherein the inbound block of metadata is associated with an inbound descriptor indicative of one or more properties of metadata comprised within the inbound block of metadata, wherein the one or more properties comprise a PCM processing parameter indicative of whether or not the metadata of the inbound block is to be discarded by an encoder, subject to a modification of the set of PCM samples and/or the extracted metadata;
• and
• generating a signature value for the set of decoded PCM samples and the extracted metadata, using a decoder secure key;
• passing the set of decoded PCM samples, the extracted metadata and the generated signature value to a corresponding encoder;
• and
• at the encoder
• receiving a set of PCM samples and associated metadata;
• receiving a signature value;
• determining whether the received signature value is valid for the received set of PCM samples and associated metadata, using an encoder secure key;
• and
• generating an outbound content frame of the outbound bitstream from the received set of PCM samples and generating an associated outbound metadata frame of the outbound bitstream from the inbound metadata frame based on the inbound descriptor, if the received signature is valid.