[FFmpeg-devel] [PATCH] EBU Tech 3285 – Supplement 3 - Peak Envelope Chunk encoder

[Michael Niedermayer]

On Wed, May 28, 2014 at 09:11:47PM +0200, Georg Lippitsch wrote:
> Am 28.05.2014, 13:04 Uhr, schrieb Michael Niedermayer <michaelni at gmx.at>:
> 
> >>+    now0 = av_gettime();
> >>+    now_secs = now0 / 1000000;
> >>+    strftime(timestamp, 28, "%Y:%m:%d:%H:%M:%S:",
> >>localtime(&now_secs));
> >>+    av_strlcatf(timestamp, 28, "%03d", (int)((now0 / 1000) % 1000));
> >
> >this cant be done when AVFMT_FLAG_BITEXACT is set.
> >Also what purpose does it serve to store the muxing time ?
> >This poses a security issue as it leaks information about the time
> >as well as the environment
> >I was not able to find any hint in the specification about the use
> >of this field
> 
> The spec says: "A C string containing the time stamp of the creation
> of the peak data", which from my understanding is the same as the
> muxing time.
> Since this code will mainly be used to create files for archival
> purpose, storing the muxing time will certainly be useful to keep
> track of when was something created. Indeed, for BITEXACT mode this
> is improper, so I could write some fake timestamp in that case.

> For your security concerns, I don't have any proper solution except
> violating the specs. What would you suggest?

i guess it should be documented, have no better idea ATM


> 
> >>+                wav->peak_maxpos[c] =
> >>FFMAX(wav->peak_maxpos[c], *(int16_t*)(pkt->data + i));
> >>+                wav->peak_maxneg[c] =
> >>FFMIN(wav->peak_maxneg[c], *(int16_t*)(pkt->data + i));
> >
> >AV_RL16()
> 
> AV_RL16 casts to uint16_t*, are you sure this will work?

hmm, then (int16_t)AV_RL16()

the issue with the code as it is, is that it wont work on big endian


[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Democracy is the form of government in which you can choose your dictator
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