unexpected video reencoding when downloading an unusual video from youtube

[attila-lendvai]

a simple invocation results in ffmpeg and video reencoding?

$ youtube-dl --continue --title "https://www.youtube.com/watch?v=_DFKJ2AXmNw"
[youtube] Setting language
[youtube] _DFKJ2AXmNw: Downloading video webpage
[youtube] _DFKJ2AXmNw: Downloading video info webpage
[youtube] _DFKJ2AXmNw: Extracting video information
[youtube] _DFKJ2AXmNw: Downloading formats manifest
[download] Destination: Liberty Talk 004 - Cody Wilson - 3D Printing and the Liberator, Dark Wallet-_DFKJ2AXmNw.mp4
ffmpeg version 0.8.6-6:0.8.6-1, Copyright (c) 2000-2013 the Libav developers
built on Mar 24 2013 18:40:26 with gcc 4.7.2
*** THIS PROGRAM IS DEPRECATED ***
This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
[applehttp @ 0x188b460] Estimating duration from bitrate, this may be inaccurate
Input #0, applehttp, from 'http://www.youtube.com/api/manifest/hls_playlist/id/_DFKJ2AXmNw.1/itag/95/source/yt_live_broadcast/ratebypass/yes/live/1/cmbypass/yes/newshard/yes/hls_chunk_host/www.youtube.com/gir/yes/dg_shard/_DFKJ2AXmNw.1_95/cp/U0hXSFlQV19JU0NON19RSkFGOlRYdEMwVmpva2tK/playlist_type/CLEAN/pmbypass/yes/maudio/1/sver/3/fexp/931945,936910,907231,907240/upn/RtNXFwdz3s4/ip/92.47.216.190/ipbits/8/expire/1383959549/sparams/ip,ipbits,expire,id,itag,source,ratebypass,live,cmbypass,newshard,hls_chunk_host,gir,dg_shard,cp,playlist_type,pmbypass,maudio/signature/943F20DE63FDD03D5224ED2AE48D6D75B2379543.93FE597F16E0FA8ACB895DB4CAEE2602E0A243DB/key/dg_yt0/file/index.m3u8':
Duration: 00:56:01.00, start: 1130.369000, bitrate: N/A
Stream #0.0: Video: h264 (Main), yuv420p, 1280x720 [PAR 1:1 DAR 16:9], 30 tbr, 90k tbn, 60 tbc
Stream #0.1: Audio: aac, 48000 Hz, stereo, s16
[buffer @ 0x1f572c0] w:1280 h:720 pixfmt:yuv420p
[libx264 @ 0x1e957a0] using SAR=1/1
[libx264 @ 0x1e957a0] using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.2 AVX
[libx264 @ 0x1e957a0] profile Main, level 3.1
[libx264 @ 0x1e957a0] 264 - core 123 r2189 35cf912 - H.264/MPEG-4 AVC codec - Copyleft 2003-2012 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=0 b_adapt=1 b_bias=0 direct=1 weightb=0 open_gop=1 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.25 aq=1:1.00
Output #0, mp4, to 'Liberty Talk 004 - Cody Wilson - 3D Printing and the Liberator, Dark Wallet-_DFKJ2AXmNw.mp4.part':
Metadata:
encoder : Lavf53.21.1
Stream #0.0: Video: libx264, yuv420p, 1280x720 [PAR 1:1 DAR 16:9], q=-1--1, 30 tbn, 30 tbc
Stream #0.1: Audio: libvo_aacenc, 48000 Hz, stereo, s16, 200 kb/s
Stream mapping:
Stream #0.0 -> #0.0
Stream #0.1 -> #0.1
Press ctrl-c to stop encoding
^Came= 83 fps= 32 q=29.0 size= 193kB time=1.37 bitrate=1159.4kbits/s
ERROR: Interrupted by user
alendvai@lelap:/tmp$ frame= 88 fps= 17 q=29.0 Lsize= 437kB time=2.90 bitrate=1233.8kbits/s
video:363kB audio:71kB global headers:0kB muxing overhead 0.772843%
frame I:2 Avg QP:19.77 size: 43232
[libx264 @ 0x1e957a0] frame P:30 Avg QP:20.96 size: 7845
[libx264 @ 0x1e957a0] frame B:56 Avg QP:24.56 size: 871
[libx264 @ 0x1e957a0] consecutive B-frames: 13.6% 2.3% 6.8% 77.3%
[libx264 @ 0x1e957a0] mb I I16..4: 39.2% 0.0% 60.8%
[libx264 @ 0x1e957a0] mb P I16..4: 7.0% 0.0% 3.4% P16..4: 34.0% 5.7% 2.0% 0.0% 0.0% skip:48.0%
[libx264 @ 0x1e957a0] mb B I16..4: 0.2% 0.0% 0.0% B16..8: 16.0% 0.4% 0.0% direct: 0.5% skip:82.8% L0:51.5% L1:47.3% BI: 1.1%
[libx264 @ 0x1e957a0] coded y,uvDC,uvAC intra: 39.6% 73.2% 19.1% inter: 2.5% 12.6% 0.1%
[libx264 @ 0x1e957a0] i16 v,h,dc,p: 35% 26% 14% 25%
[libx264 @ 0x1e957a0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 42% 21% 13% 4% 4% 6% 3% 4% 2%
[libx264 @ 0x1e957a0] i8c dc,h,v,p: 46% 22% 25% 7%
[libx264 @ 0x1e957a0] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0x1e957a0] ref P L0: 75.7% 8.2% 11.0% 5.1%
[libx264 @ 0x1e957a0] ref B L0: 91.5% 8.5%
[libx264 @ 0x1e957a0] kb/s:1010.66
Received signal 2: terminating.

[jaimeMF]

That videos uses the HTTP Live Streaming protocol, we don't have our own downloader for it, so we have to use ffmpeg. Now it won't reencode the video, it will just download it (it really reduces memory and CPU consumption).
Thanks for the report.