Non-monotonous DTS in output for audio stream using ffmpeg concat -

this asked in ffmpeg - non-monotonous dts on concat. poster opted mp4box after getting no reply. however, stick ffmpeg think quicker.

i concatenating files text file list of mp4 files have been encoded @ same time using same codecs there should no incompatibility between files.

i not sure non-monotonous dts (anyone?) worried may produce glitches in concatenated files. seem ok there evidence of artefacts in sound. can tweak command line rid of error, , speed concatenation process? using python subprocess call , file passed function list of files. function decorator timer function profiling. have tried system ffmpeg not static build, , has same problem.

@fn_timer def concat(file):     proc = call(['/opt/jane_ng/jane_nodejs/ffmpeg-git-20150308-64bit-static/ffmpeg', '-f', 'concat', '-i', file, '-c', 'copy', '-y', 'testconcat.mp4']) 

when run this, following output:

ffmpeg version n-45007-g9d7e42e-   http://johnvansickle.com/ffmpeg/    copyright (c) 2000-2015 ffmpeg developers    built gcc 4.9.2 (debian 4.9.2-10)    configuration: --enable-gpl --enable-version3 --disable-shared --disable-debug --enable-runtime-cpudetect --enable-libmp3lame --enable-libx264 --enable-libx265 --enable-libwebp --enable-libspeex --enable-libvorbis --enable-libvpx --enable-libfreetype --enable-fontconfig --enable-libxvid --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-gray --enable-libopenjpeg --enable-libopus --enable-libass --enable-gnutls --enable-libvidstab --cc=gcc-4.9    libavutil      54. 20.100 / 54. 20.100    libavcodec     56. 26.100 / 56. 26.100    libavformat    56. 25.101 / 56. 25.101    libavdevice    56.  4.100 / 56.  4.100    libavfilter     5. 12.100 /  5. 12.100    libswscale      3.  1.101 /  3.  1.101    libswresample   1.  1.100 /  1.  1.100    libpostproc    53.  3.100 / 53.  3.100  [concat @ 0x31bdd80] not find codec parameters stream 2 (unknown: none): unknown codec  consider increasing value 'analyzeduration' , 'probesize' options  input #0, concat, '/opt/combinatoria/generator/concatfiles/concat.txt':    duration: n/a, start: 0.000000, bitrate: 1625 kb/s      stream #0:0: video: h264 (main) (avc1 / 0x31637661), yuv420p(tv), 960x540 [sar 1:1 dar 16:9], 1561 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc      stream #0:1: audio: aac (he-aac) (mp4a / 0x6134706d), 44100 hz, stereo, fltp, 64 kb/s      stream #0:2: unknown: none  output #0, mp4, 'testconcat.mp4':    metadata:      encoder         : lavf56.25.101      stream #0:0: video: h264 ([33][0][0][0] / 0x0021), yuv420p, 960x540 [sar 1:1 dar 16:9], q=2-31, 1561 kb/s, 25 fps, 25 tbr, 90k tbn, 90k tbc      stream #0:1: audio: aac ([64][0][0][0] / 0x0040), 44100 hz, stereo, 64 kb/s  stream mapping:    stream #0:0 -> #0:0 (copy)    stream #0:1 -> #0:1 (copy)  press [q] stop, [?]  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 253952, current: 250488; changing 253953. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 253953, current: 252536; changing 253954. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 754296, current: 751464; changing 754297. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 754297, current: 753512; changing 754298. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 974696, current: 971964; changing 974697. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 974697, current: 974012; changing 974698. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 1340604, current: 1337112; changing 1340605. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 1340605, current: 1339160; changing 1340606. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 1746712, current: 1742832; changing 1746713. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 1746713, current: 1744880; changing 1746714. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 2119664, current: 2116800; changing 2119665. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 2119665, current: 2118848; changing 2119666. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 2274496, current: 2272032; changing 2274497. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 2274497, current: 2274080; changing 2274498. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 2685728, current: 2683044; changing 2685729. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 2685729, current: 2685092; changing 2685730. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 2850980, current: 2847096; changing 2850981. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 2850981, current: 2849144; changing 2850982. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 3033464, current: 3030552; changing 3033465. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 3033465, current: 3032600; changing 3033466. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 3384856, current: 3381588; changing 3384857. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 3384857, current: 3383636; changing 3384858. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 3760468, current: 3757320; changing 3760469. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 3760469, current: 3759368; changing 3760470. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 3990792, current: 3988404; changing 3990793. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 3990793, current: 3990452; changing 3990794. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 4295604, current: 4291812; changing 4295605. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 4295605, current: 4293860; changing 4295606. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 4750564, current: 4746924; changing 4750565. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 4750565, current: 4748972; changing 4750566. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 5025452, current: 5022108; changing 5025453. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 5025453, current: 5024156; changing 5025454. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 5271964, current: 5269068; changing 5271965. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 5271965, current: 5271116; changing 5271966. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 5707340, current: 5704776; changing 5707341. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 5707341, current: 5706824; changing 5707342. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 6003784, current: 6001128; changing 6003785. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 6003785, current: 6003176; changing 6003786. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 6371816, current: 6368040; changing 6371817. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 6371817, current: 6370088; changing 6371818. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 6875944, current: 6872544; changing 6875945. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 6875945, current: 6874592; changing 6875946. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 7042528, current: 7040124; changing 7042529. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 7042529, current: 7042172; changing 7042530. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 7314556, current: 7311780; changing 7314557. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 7314557, current: 7313828; changing 7314558. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 7541156, current: 7537572; changing 7541157. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 7541157, current: 7539620; changing 7541158. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 7795620, current: 7791588; changing 7795621. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 7795621, current: 7793636; changing 7795622. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 8063972, current: 8059716; changing 8063973. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 8063973, current: 8061764; changing 8063974. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 8063974, current: 8063812; changing 8063975. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 8350532, current: 8347248; changing 8350533. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 8350533, current: 8349296; changing 8350534. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 8656496, current: 8652420; changing 8656497. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 8656497, current: 8654468; changing 8656498. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 8902276, current: 8899380; changing 8902277. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 8902277, current: 8901428; changing 8902278. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 9159476, current: 9156924; changing 9159477. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 9159477, current: 9158972; changing 9159478. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 9468220, current: 9465624; changing 9468221. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 9468221, current: 9467672; changing 9468222. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 9748248, current: 9744336; changing 9748249. may result in incorrect timestamps in output file.  [mp4 @ 0x3255080] non-monotonous dts in output stream 0:1; previous: 9748249, current: 9746384; changing 9748250. may result in incorrect timestamps in output file.  frame= 5637 fps=0.0 q=-1.0 lsize=   45617kb time=00:03:45.60 bitrate=1656.4kbits/s      video:43701kb audio:1792kb subtitle:0kb other streams:0kb global headers:0kb muxing overhead: 0.272048%  total time running concat: 0.451297044754 seconds

this process absolutely key current project or clarification appreciated.

eventually, worked , streamed without hitch once re-encoded source files fed ffmpeg concat command. no dts errors when processing , streamed audio in sync server.