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20th April 2016, 20:05 | #1 | Link |
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IDR vs I frame
Hi experts,
Whats the difference between I and IDR frame? Either length of GOP consist of total number of frames between two IDR frames or between two I frames? This is really confusing for me. Any help would be highly appreciated. |
20th April 2016, 20:18 | #2 | Link |
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IDR-Frame clears the reference picture buffer, i.e. no frame after IDR can reference any frame before IDR. That's not the case with "normal" I-Frame, i.e. P- or B-Frame after I-Frame can use as reference frames before I-Frame.
In other words: You are always "cleanly" start decoding at an IDR-Frame, which is not (in general) possible with a "normal" I-Frame.
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21st April 2016, 08:57 | #3 | Link | |
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21st April 2016, 09:08 | #4 | Link |
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Not sure what 65 is supposed to mean, but IDRs are nal_unit_type 5, and normal I frames just use nal_unit_type 1 (like any other frames as well)
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LAV Filters - open source ffmpeg based media splitter and decoders Last edited by nevcairiel; 21st April 2016 at 14:35. |
21st April 2016, 15:55 | #5 | Link | |
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21st April 2016, 19:08 | #6 | Link |
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Are you sure the NAL unit type is encoded as a whole byte?
Probably you need to understand what the individual bits (flags) in this byte sequence actually mean. Then you might be able to tell whether this contains the NAL unit type - and, if so, what the NAL unit type is
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21st April 2016, 19:23 | #7 | Link |
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nal unit type is 5 bits, i think. 0x1f mask of the first byte after the start code.
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LAV Filters - open source ffmpeg based media splitter and decoders Last edited by nevcairiel; 21st April 2016 at 19:27. |
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h.264, i-frame, idr |
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