The problem seems to be with all input formats. Also, the problem is limited to the asf/wmv wrapper (asf-enc.c), not the codec itself - WMV2 conversions to the .avi container work flawlessly. "-vcodec copy" into a .asf/wmv wrapper will then demonstrate the problem on playback. Windows Media Player for Windows and Flip4Mac's QuickTime components both cause stalls that are not rectified until the next keyframe. ffmpeg itself has a little trouble decoding a self-made stream. Example: FFmpeg version SVN-r6213, Copyright (c) 2000-2004 Fabrice Bellard configuration: --enable-pthreads --disable-network --disable- audio-oss --disable-v4l --disable-bktr --disable-dv1394 --disable- ffserver --disable-ffplay --enable-faac --enable-faad --enable-a52 -- enable-x264 --enable-mp3lame --enable-gpl --disable-debug --enable- amr_wb --enable-amr_nb libavutil version: 49.0.0 libavcodec version: 51.14.0 libavformat version: 50.5.0 built on Sep 23 2006 13:58:32, gcc: 4.0.1 (Apple Computer, Inc. build 5363) Seems that stream 0 comes from film source: 1000.00 (1000/1) -> 29.97 (30000/1001) Input #0, asf, from '/Users/tylerl/Desktop/wmvtest1.wmv': Duration: 00:01:13.0, start: 2.000000, bitrate: 293 kb/s Stream #0.0: Video: wmv2, yuv420p, 320x240, 29.97 fps(r) Stream #0.1: Audio: mp3, 22050 Hz, mono, 64 kb/s Output #0, asf, to 'wmvtest2.wmv': Stream #0.0: Video: msmpeg4, yuv420p, 320x240, q=2-31, 200 kb/s, 29.97 fps(c) Stream #0.1: Audio: mp3, 22050 Hz, mono, 64 kb/s Stream mapping: Stream #0.0 -> #0.0 Stream #0.1 -> #0.1 Press [q] to stop encoding [wmv2 @ 0x512298]overreading 4 bits [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors overread, skip -6 enddists: -1 -1 [wmv2 @ 0x512298]overreading 4 bits [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors invalid new backstep 112 overread, skip -7 enddists: -1 -1B time=6.5 bitrate= 427.5kbits/s [wmv2 @ 0x512298]overreading 58 bitsme=14.2 bitrate= 360.1kbits/s [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors [wmv2 @ 0x512298]overreading 5 bitsime=22.0 bitrate= 335.0kbits/s [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors invalid new backstep 108 [wmv2 @ 0x512298]overreading 6 bits [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors [wmv2 @ 0x512298]overreading 65 bitsme=29.4 bitrate= 328.0kbits/s [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors [wmv2 @ 0x512298]overreading 30 bits [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors [wmv2 @ 0x512298]overreading 30 bits [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors [wmv2 @ 0x512298]overreading 28 bitsme=37.0 bitrate= 319.9kbits/s [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors [wmv2 @ 0x512298]overreading 26 bits [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors [wmv2 @ 0x512298]overreading 2 bits [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors [wmv2 @ 0x512298]overreading 6 bitstime=44.5 bitrate= 316.2kbits/s [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors overread, skip -5 enddists: -4 -4 [wmv2 @ 0x512298]overreading 27 bitsme=52.4 bitrate= 308.3kbits/s [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors overread, skip -5 enddists: -4 -4 [wmv2 @ 0x512298]overreading 8 bitstime=67.8 bitrate= 305.8kbits/s [wmv2 @ 0x512298]concealing 300 DC, 300 AC, 300 MV errors frame= 2249 q=19.2 Lsize= 1kB time=75.0 bitrate= 0.1kbits/s video:2077kB audio:586kB global headers:0kB muxing overhead -99.979575% Here's the log and cmdline used to create that file: carl:~ tylerl$ VisualHub/ffmpeg -i /Users/tylerl/Desktop/ whinerscantbelosers-pants.flv -vcodec wmv2 -g 300 ~/Desktop/wmvtest1.wmv FFmpeg version SVN-r6213, Copyright (c) 2000-2004 Fabrice Bellard configuration: --enable-pthreads --disable-network --disable- audio-oss --disable-v4l --disable-bktr --disable-dv1394 --disable- ffserver --disable-ffplay --enable-faac --enable-faad --enable-a52 -- enable-x264 --enable-mp3lame --enable-gpl --disable-debug --enable- amr_wb --enable-amr_nb libavutil version: 49.0.0 libavcodec version: 51.14.0 libavformat version: 50.5.0 built on Sep 23 2006 13:58:32, gcc: 4.0.1 (Apple Computer, Inc. build 5363) Seems that stream 1 comes from film source: 1000.00 (1000/1) -> 29.97 (30000/1001) Input #0, flv, from '/Users/tylerl/Desktop/whinerscantbelosers- pants.flv': Duration: 00:01:15.0, start: 0.000000, bitrate: N/A Stream #0.0: Audio: mp3, 22050 Hz, mono Stream #0.1: Video: flv, yuv420p, 320x240, 29.97 fps(r) Output #0, asf, to '/Users/tylerl/Desktop/wmvtest1.wmv': Stream #0.0: Video: wmv2, yuv420p, 320x240, q=2-31, 200 kb/s, 29.97 fps(c) Stream #0.1: Audio: mp3, 22050 Hz, mono, 64 kb/s Stream mapping: Stream #0.1 -> #0.0 Stream #0.0 -> #0.1 Press [q] to stop encoding frame= 2249 q=15.2 Lsize= 1kB time=75.0 bitrate= 0.1kbits/s video:1923kB audio:586kB global headers:0kB muxing overhead -99.978402% -Tyler Loch Techspansion LLC http://www.techspansion.com