These functions are using the POSIX clock_gettime() function with the CLOCK_MONOTONIC clock id. If these are not present on the targeted platform, the new functions will fallback on using the original realtime functions av_gettime() and av_usleep(). Monotonic support can be added on other platforms with their equivalent native system API eventually if possible. Whenever time is requested to measure relative time, the monotonic clock, when available, is superior to the system realtime clock because it is not affected by discontinuous jumps in the system time In a future step, offering the flexibility to let the user choose between rt and monotonic clock for avdevices packets will be investigated. It is very easy to experience the issues that this patch attempt to address by rewinding back in the past the system time while ffmpeg is running. this is breaking the ffmpeg report printing (ffmepg.c:print_report()) and the the rate emulator functionality (-re) without the patch.
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| @@ -15,6 +15,9 @@ libavutil: 2012-10-22 · 14 unmodified lines | ||
| 15 | 15 | |
| 16 | 16 | API changes, most recent first: |
| 17 | 17 | |
| 18 | +2014-05-xx - xxxxxxx - lavu 52.84.100 - time.h | |
| 19 | + Add av_gettime_relative() av_gettime_relative_is_monotonic() | |
| 20 | + | |
| 18 | 21 | 2014-05-xx - xxxxxxx - lavf 55.17.0 - avformat.h |
| 19 | 22 | Add AVMFT_FLAG_BITEXACT flag. Muxers now use it instead of checking |
| 20 | 23 | CODEC_FLAG_BITEXACT on the first stream. |