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podborski
reviewed
Jan 27, 2026
| * Tile List OBUs shall not be used | ||
| * Temporal Delimiters may be removed | ||
| * Redundant Frame Headers and Padding OBUs may be used. | ||
| * Mastering display colour volume SEI message: tt is recommended that HDR Bitstreams using PQ10 set a valid number to primary_chromaticity_x, primary_chromaticity_y, white_point_chromaticity_x, white_point_chromaticity_y, luminance_max and luminance_min fields. If the proper value for all these fields is unknown, it is recommended that no mastering display colour volume SEI message is present in the HDR Bitstream using PQ10; or if the proper value for any one of the following fields are unknown, primary_chromaticity_x, primary_chromaticity_y, white_point_chromaticity_x, white_point_chromaticity_y or luminance_max, it is recommended that the unknown field is set to 0. The lowest value for luminance_min that is valid without ambiguity is 0.0001, when viewing a Reference Monitor calibrated while viewing a test pattern (such as PLUGE for example). Hence it is recommended that: 1) an unknown value for luminance_min should be signalled with value 0; 2) a known value for luminance_min should be signalled with a value larger than or equal to 0.0001. |
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SEI -> metadata OBUs.
metadata_hdr_mdcv
podborski
reviewed
Jan 27, 2026
| * Temporal Delimiters may be removed | ||
| * Redundant Frame Headers and Padding OBUs may be used. | ||
| * Mastering display colour volume SEI message: tt is recommended that HDR Bitstreams using PQ10 set a valid number to primary_chromaticity_x, primary_chromaticity_y, white_point_chromaticity_x, white_point_chromaticity_y, luminance_max and luminance_min fields. If the proper value for all these fields is unknown, it is recommended that no mastering display colour volume SEI message is present in the HDR Bitstream using PQ10; or if the proper value for any one of the following fields are unknown, primary_chromaticity_x, primary_chromaticity_y, white_point_chromaticity_x, white_point_chromaticity_y or luminance_max, it is recommended that the unknown field is set to 0. The lowest value for luminance_min that is valid without ambiguity is 0.0001, when viewing a Reference Monitor calibrated while viewing a test pattern (such as PLUGE for example). Hence it is recommended that: 1) an unknown value for luminance_min should be signalled with value 0; 2) a known value for luminance_min should be signalled with a value larger than or equal to 0.0001. | ||
| * Content light level information SEI message: HDR Bitstreams using PQ10 may contain a content light level SEI message as specified in Recommendation ITU-T H.274 / ISO/IEC 23002-7 [CITE]. If a content light level information SEI message is present, it shall be transmitted with every random access point. Note: In some cases, such as live and linear broadcast, it may not be possible to calculate the values of max_cll and max_fall fields. If the value for the fields max_cll and max_fall is known, it is recommended that HDR Bitstreams using PQ10 include valid settings. If the value for these fields is unknown, it is recommended that no content light level information SEI message is present in the HDR Bitstream using PQ10; or if the value for any one of these fields is unknown, it is recommended that the unknown field is set to 0. |
tdaede
reviewed
Jan 27, 2026
| * The time interval between two successive changes in seq_profile, seq_tier or seq_level_idx carried in the sequence_header_obu syntax structure shall be greater than or equal to one second. | ||
| * The still_picture and reduced_still_picture_header flags shall both be set to 0. | ||
| * The encoder shall place RAPs in the PES at least once every 2 seconds. Where rapid channel change times are important or for applications such as PVR it may be appropriate for RAPs to occur more frequently, such as every 1 second. The time interval between successive RAPs shall be measured as the difference between their respective DTS values. | ||
| * The display aspect ratio of the AV1 coded frame, after conformance cropping is applied, shall be 16:9. |
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I think the display aspect ratio requirement is too strict for the more general SRT use case.
podborski
reviewed
Jan 27, 2026
| * Tile List OBUs shall not be used | ||
| * Temporal Delimiters may be removed | ||
| * Redundant Frame Headers and Padding OBUs may be used. | ||
| * Mastering display colour volume SEI message: tt is recommended that HDR Bitstreams using PQ10 set a valid number to primary_chromaticity_x, primary_chromaticity_y, white_point_chromaticity_x, white_point_chromaticity_y, luminance_max and luminance_min fields. If the proper value for all these fields is unknown, it is recommended that no mastering display colour volume SEI message is present in the HDR Bitstream using PQ10; or if the proper value for any one of the following fields are unknown, primary_chromaticity_x, primary_chromaticity_y, white_point_chromaticity_x, white_point_chromaticity_y or luminance_max, it is recommended that the unknown field is set to 0. The lowest value for luminance_min that is valid without ambiguity is 0.0001, when viewing a Reference Monitor calibrated while viewing a test pattern (such as PLUGE for example). Hence it is recommended that: 1) an unknown value for luminance_min should be signalled with value 0; 2) a known value for luminance_min should be signalled with a value larger than or equal to 0.0001. |
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There was a contribution to the last MPEG meeting mentioning that there order of chroma information is different between HEVC and AV1, and some investigation is happening in ISOBMFF TuC. Maybe something to be aware of in the context of this spec.
podborski
reviewed
Jan 27, 2026
| * The time interval between two successive changes in seq_profile, seq_tier or seq_level_idx carried in the sequence_header_obu syntax structure shall be greater than or equal to one second. | ||
| * The still_picture and reduced_still_picture_header flags shall both be set to 0. | ||
| * The encoder shall place RAPs in the PES at least once every 2 seconds. Where rapid channel change times are important or for applications such as PVR it may be appropriate for RAPs to occur more frequently, such as every 1 second. The time interval between successive RAPs shall be measured as the difference between their respective DTS values. | ||
| * The display aspect ratio of the AV1 coded frame, after conformance cropping is applied, shall be 16:9. |
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This restriction seems to harsh.
podborski
reviewed
Jan 27, 2026
| * Mastering display colour volume SEI message: tt is recommended that HDR Bitstreams using PQ10 set a valid number to primary_chromaticity_x, primary_chromaticity_y, white_point_chromaticity_x, white_point_chromaticity_y, luminance_max and luminance_min fields. If the proper value for all these fields is unknown, it is recommended that no mastering display colour volume SEI message is present in the HDR Bitstream using PQ10; or if the proper value for any one of the following fields are unknown, primary_chromaticity_x, primary_chromaticity_y, white_point_chromaticity_x, white_point_chromaticity_y or luminance_max, it is recommended that the unknown field is set to 0. The lowest value for luminance_min that is valid without ambiguity is 0.0001, when viewing a Reference Monitor calibrated while viewing a test pattern (such as PLUGE for example). Hence it is recommended that: 1) an unknown value for luminance_min should be signalled with value 0; 2) a known value for luminance_min should be signalled with a value larger than or equal to 0.0001. | ||
| * Content light level information SEI message: HDR Bitstreams using PQ10 may contain a content light level SEI message as specified in Recommendation ITU-T H.274 / ISO/IEC 23002-7 [CITE]. If a content light level information SEI message is present, it shall be transmitted with every random access point. Note: In some cases, such as live and linear broadcast, it may not be possible to calculate the values of max_cll and max_fall fields. If the value for the fields max_cll and max_fall is known, it is recommended that HDR Bitstreams using PQ10 include valid settings. If the value for these fields is unknown, it is recommended that no content light level information SEI message is present in the HDR Bitstream using PQ10; or if the value for any one of these fields is unknown, it is recommended that the unknown field is set to 0. | ||
| * The time interval between two successive changes in seq_profile, seq_tier or seq_level_idx carried in the sequence_header_obu syntax structure shall be greater than or equal to one second. | ||
| * The still_picture and reduced_still_picture_header flags shall both be set to 0. |
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In general, the group expressed some concerns in terms of restrictions. We need to study which restrictions are really necessary for this spec.
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