Does RTMP still have the 4GB problem?

C E Macfarlane c.e.macfarlane at
Sun Jul 5 23:30:15 PDT 2015

>     -----Original Message-----
>     From: get_iplayer [mailto:get_iplayer-bounces at]On
>     Behalf Of Vangelis forthnet
>     Sent: 06 July 2015 01:50
>     To: get_iplayer at
>     Subject: Re: Does RTMP still have the 4GB problem?
>     On Mon Jul 6 00:11:22 BST 2015, C E Macfarlane wrote:
>     > Does RTMP still have the 4GB problem?
>     Hi - please read:
>     ... do not be lazy and check all the links referenced!

Done, but I'd read most of them already ...

>     > I've been encountering problems playing back
>     > some of the long Wimbledon programmes.
>     > The files play so far, and then hang.
>     > I suspect that this is the rtmpdump 4GB problem...
>     > (snip)
>     > my download speeds are very slow
>     Are you on Windows?

No.  The files are downloaded by Linux running on an embedded device, but
played back on a W7 laptop.

>     Were those huge FLV files downloaded in one go
>     or was it that due to your slow connection rtmpdump
>     timed out and had to resume (possibly a number of times)
>     during the download?

As it now takes place automatically from a cron job, I cannot be entirely
sure  -  one download has definitely stalled, but I haven't yet attempted to
play that particular *.flv file.  The problems have occurred in large *.mp4
files that appeared to have downloaded successfully.  Smaller *.mp4 files
nearly always download correctly.

>     The last case may have resulted in a corrupt FLV file
>     and that in turn could've resulted in a corrupt MP4 file
>     after the lossless remux by FFmpeg...
>     What media player did you use for playback
>     and at which point during the file's duration the hang occurs?

I tried WMP and VLC.  They both seem to give up around the same point,
around 6:20:00 in.

>     "flashhd" files have an average file size of ca. 0.9-1.0GiB/hour

These are flashvhigh1 at around .63GB/hr, so the stall does take place at
the 4GB point.

>     (avg BR=2400kbps). What is the file size reported by
>     your File Manager (Windows Explorer?) and what is
>     the overall duration reported by your software player?

5,627,099KB and 8:30:37

>     It may be wise to include the "--check-duration" switch in
>     your commands (=> Print message showing recorded duration,
>     expected duration and difference between them), although
>     this is useful when large differences are reported (i.e.
>     truncated downloads).
>     Can you live with the flashvhigh files (Res=832x468,
>     BR~1500kbps)? - their size is ~ 62% the size of their
>     flashhd counterparts...

As above.

>     > I am going to have to split the downloads
>     > using --stop and --start parameters.

(Not using HD, so reply snipped)

>     Please try the newly implemented (in GiP 2.94) hlshd modes
>     (--tvmode=hlshd) - these use ffmpeg to record via HTTP, so
>     no RTMP protocol used (no 4GB limit applies to HTTP); however,
>     with your slow connection, you might still encounter problems
>     with time-outs
>     (and missed HLS fragments) if latency is introduced during download...

No, my download speeds are too slow to handle so many such huge files at

Thanks, but simply answering the questions asked would have sufficed.

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