mirror/taglib
1
0
Fork 0
mirror of https://github.com/taglib/taglib.git synced 2025-07-19 05:24:25 -04:00
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #981 from ufleisch/ufleisch/alac-without-bitrate

Browse Source 
Calculate bitrate for ALAC files without it (#961)
This commit is contained in:
Urs Fleisch
2021-01-01 11:45:12 +01:00
parent 5374cb1ac4 563fbaf82a
commit 54f5c66b65
2 changed files with 84 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
taglib/mp4/mp4properties.cpp
View File

@ -31,6 +31,27 @@
using namespace TagLib;
namespace
{
// Calculate the total bytes used by audio data, used to calculate the bitrate
long long calculateMdatLength(const MP4::AtomList &list)
{
long long totalLength = 0;
for(MP4::AtomList::ConstIterator it = list.begin(); it != list.end(); ++it) {
long length = (*it)->length;
if(length == 0)
return 0; // for safety, see checkValid() in mp4file.cpp
if((*it)->name == "mdat")
totalLength += length;
totalLength += calculateMdatLength((*it)->children);
}
return totalLength;
}
}
class MP4::Properties::PropertiesPrivate
{
public:
@ -213,7 +234,14 @@ MP4::Properties::read(File *file, Atoms *atoms)
pos += 3;
}
pos += 10;
d->bitrate = static_cast<int>((data.toUInt(pos) + 500) / 1000.0 + 0.5);
const unsigned int bitrateValue = data.toUInt(pos);
if(bitrateValue != 0 || d->length <= 0) {
d->bitrate = static_cast<int>((bitrateValue + 500) / 1000.0 + 0.5);
}
else {
d->bitrate = static_cast<int>(
(calculateMdatLength(atoms->atoms) * 8) / d->length);
}
}
}
}
@ -224,6 +252,13 @@ MP4::Properties::read(File *file, Atoms *atoms)
d->channels = data.at(73);
d->bitrate = static_cast<int>(data.toUInt(80U) / 1000.0 + 0.5);
d->sampleRate = data.toUInt(84U);
if(d->bitrate == 0 && d->length > 0) {
// There are files which do not contain a nominal bitrate, e.g. those
// generated by refalac64.exe. Calculate the bitrate from the audio
// data size (mdat atoms) and the duration.
d->bitrate = (calculateMdatLength(atoms->atoms) * 8) / d->length;
}
}
}