<div dir="ltr">System from vainfo libva info: VA-API version 0.34.0libva info: va_getDriverName() returns 0 libva info: Trying to open /usr/local/lib/dri/i965_drv_video.solibva info: Found init function __vaDriverInit_0_34 libva info: va_openDriver() returns 0vainfo: VA-API version: 0.34 (libva 1.2.2.pre1) vainfo: Driver version: Intel i965 driver - 1.2.1vainfo: Supported profile and entrypoints VAProfileNone : VAEntrypointVideoProc VAProfileMPEG2Simple : VAEntrypointVLD VAProfileMPEG2Simple : VAEntrypointEncSlice VAProfileMPEG2Main : VAEntrypointVLD VAProfileMPEG2Main : VAEntrypointEncSlice VAProfileH264Baseline : VAEntrypointVLD VAProfileH264Baseline : VAEntrypointEncSlice VAProfileH264Main : VAEntrypointVLD VAProfileH264Main : VAEntrypointEncSlice VAProfileH264High : VAEntrypointVLD VAProfileH264High : VAEntrypointEncSlice VAProfileVC1Simple : VAEntrypointVLD VAProfileVC1Main : VAEntrypointVLD VAProfileVC1Advanced : VAEntrypointVLD VAProfileJPEGBaseline : VAEntrypointVLD<div style="font-family:arial,sans-serif;font-size:13px"> </div> How to produce a video corruption with h264encode Background When encoding two files, there are four significant events: A. Begin encoding first file B. Finish encoding first file C. Begin encoding second file D. Finish encoding second file There are three possible orderings for these four events: ABCD (no overlap - first file is finished before second begins) **No corruption observed A----------B C----------D ACDB (complete overlap - the second file begins after and finishes before the first) **No corruption observed A----------------B C----D ACBD (partial overlap - the second file begins before the first file finishes) A----------B C----------D The last case ACBD (partial overlap) always results in video corruption. The video output of second file is correct up to event B. Beyond that point, the video is corrupt. Procedure To Reproduce You will need to start with a yuv formatted input file. If you don’t have one, you can create one with ffmpeg from any source video. 1. Determine how long it takes to encode the file # time /root/libva-1.2.1/test/encode/h264encode --srcyuv in.yuv -framecount 0 -f 25 -o out1.mp4 > /dev/null 2> /dev/null real 0m14.984s user 0m6.690s sys 0m10.115s So, in this example, my file takes 15 seconds to encode so I will start the second video encoding about 7 seconds after the first to make sure they overlap in the ACBD order described above. 2. Open two separate terminals. Run these commands, one in each terminal, with the 2nd command executed about 7 seconds after the first (this delay is to ensure the right overlap) # date ; time /root/libva-1.2.1/test/encode/h264encode --srcyuv in.yuv -framecount 0 -f 25 -o out1.mp4 >/dev/null 2>/dev/null ; date # date ; time /root/libva-1.2.1/test/encode/h264encode --srcyuv in.yuv -framecount 0 -f 25 -o out2.mp4 >/dev/null 2>/dev/null ; date Here is sample output (Note: h264encode output is suppressed): Terminal 1: # date ; time /root/libva-1.2.1/test/encode/h264encode --srcyuv in.yuv -framecount 0 -f 25 -o out1.mp4 >/dev/null 2>/dev/null ; date Wed Feb 12 16:44:08 CST 2014 real 0m15.084s user 0m5.698s sys 0m9.601s Wed Feb 12 16:44:23 CST 2014 Terminal 2: # date ; time /root/libva-1.2.1/test/encode/h264encode --srcyuv in.yuv -framecount 0 -f 25 -o out2.mp4 >/dev/null 2> /dev/null ; date Wed Feb 12 16:44:15 CST 2014 real 0m9.097s user 0m3.431s sys 0m5.660s Wed Feb 12 16:44:24 CST 2014 Note that the second encoding finishes only one second after the first despite being started 7 seconds later. Testing with different offsets confirms the second encoding always finishes immediately after the first, regardless of start time. Verify Corruption Exists 1. Use the file compare utility cmp to compare files: #cmp – b out1.mp4 out2.mp42. If the files are identical, there will be no output. What I see is the files begin showing differences at a position relatively proportional to my start offset. For example, starting 7.5 seconds after the first video, using 15 second videos, the corruption appears in the middle of the file. If you were to play the file, you would observe the file plays correctly to the point of corruption. At that point, the video freezes or flickers between 2 frames. Note: We're observing these corruptions in our own code, which is unrelated to h264encode. We used h264encode to eliminate all variables and exonerate our code. </div>