  Scalable lossless video coding is an important aspect for many professional
applications. Wavelet-based video coding decomposes an input sequence into a
lowpass and a highpass subband by filtering along the temporal axis. The
lowpass subband can be used for previewing purposes, while the highpass subband
provides the residual content for lossless reconstruction of the original
sequence. The recursive application of the wavelet transform to the lowpass
subband of the previous stage yields coarser temporal resolutions of the input
sequence. This allows for lower bit rates, but also affects the visual quality
of the lowpass subband. So far, the number of total decomposition levels is
determined for the entire input sequence in advance. However, if the motion in
the video sequence is strong or if abrupt scene changes occur, a further
decomposition leads to a low-quality lowpass subband. Therefore, we propose a
content adaptive wavelet transform, which locally adapts the depth of the
decomposition to the content of the input sequence. Thereby, the visual quality
of the low-pass subband is increased by up to 10.28 dB compared to a uniform
wavelet transform with the same number of total decomposition levels, while the
required rate is reduced by 1.06% additionally.
