Last one: I need to edit some movies (conference recording, mostly slide shows with audio). It is simple enough. Clear fluff from the front and the end as people fiddle with the presentation, insert a clean slide title at the front and a closing slide at the end. I managed to get that done.
Regarding what options you have to make the file a smaller size, probably the easiest is to share it to Email instead of File, and under the Resolution options you will have options to make the video Small, Medium, or Large. You can really compress it down. I tried it and compressed a 47.8 mb video down to 1.7 mb using the small option. The Medium or small options would give you a larger file, of course.
The likely answer is that your input video was very highly compressed and iMovie unpacked it for editing and rendered a less compressed version. Hence bigger size. Less compressed is better for quality and editing, and is desirable unless one intends to upload to the internet, or email it somewhere, or has storage space limitations.
But iMovie does not know that: it assumes I'm actually editing a real movie where the scene changes constantly, so it applies a reasonable bitrate, that essentially matches the 360p/480p internet movies.
This has the effect to convert the mp4 files to a lower bitrate (160kbps). The resulting size is just a little higher that the originals, and there is no degradation in quality (keeping in mind that the movies are just slide shows with and audio track).
Results of reconstruction are 3D data volumes with 16-bit values for x-ray attenuation (white = higher attenuation) at each volume element (voxel). Full volume files in NetCDF format are 425 MB for binned runs, and 3.4GB for unbinned runs. The latter cannot be manipulated using IDL on a 32-bit operating system. These volumes were cropped to contain only the track, for convenience. In run 'e', for example, visual inspection establishes that the track is contained in the volume range 362 < x < 428, 230 < y < 270, and the full range of z. Cropping the volume to this range decreases its size by a factor of 10. Results are presented in two forms: MPG format movies, and stacks of TIF format images. The MPG files are compressed, and limited to 256 (8-bit) grayscales. The TIF can be output by the software as 16-bit arrays, but for the purposes here are limited to 256 bits also. Frame stacks are presented in Digital Appendix 2, the cropped volume, thresholded, is presented as Digital Appendix 3, and movies are presented in Digital Appendix 4.
Typical microangiogram movies showing an image field of 5 mm x 5 mm square. The study area was delineated by a wire of 50 micrometer diameter. These videos were acquired for 10 s at 50 frames per second. Movie 1: perfusion in normal tissue.. DOI: 10.1107/S1600577517008372/ay5497sup1.avi
Typical microangiogram movies showing an image field of 5 mm x 5 mm square. The study area was delineated by a wire of 50 micrometer diameter. These videos were acquired for 10 s at 50 frames per second. Movie 2: perfusion in a tumor.. DOI: 10.1107/S1600577517008372/ay5497sup2.avi
Achieving a good localization of faces on video frames is of high importance for an application such as video indexing. Face localization on movies is an ambiguous task due to various scale, pose and lighting conditions.
B) Hierarchical Clustering: An algorithm to cluster face images found in feature length movies and generally in video sequences is proposed. A novel method for creating a dissimilarity matrix using SIFT image features is introduced. This dissimilarity matrix is used as an input in a hierarchical average linkage clustering algorithm, which finally yields the clustering result.
Signal loss occurring in physical communication channels is unavoidable. In the case of transmission of highly compressed video sequences by the MPEG-2 codec, this leads to significant errors observed to the reconstructed frames at the decoder side. These errors fall into two categories:
Non-linear optical techniques have been exploited to develop a new generation of optical microscopes with unprecedented capabilities. These new capabilities include the ability to use near-infrared (IR) light to induce absorption, and hence fluorescence, from fluorophores that absorb in the ultraviolet wavelength region. Other capabilities of non-linear microscopes include improved spatial and temporal resolution without the use of pinholes or slits for spatial filtering, improved signal strength, deeper penetration into thick, highly scattering tissues, and confinement of photobleaching to the focal volume . Two-photon excitation offers major advantages when working in the thick tissue, such as brain slices or developing embryos, due to the dramatically reduced effects of light scattering. This is partly because the longer red and near-IR wavelengths used for two photon illumination penetrate deeper into biological tissue with less absorption and scattering. However, the main advantage comes from the non-linear excitation. The requirement for two coincident (or near coincident) photons to achieve excitation of the fluorophore means that only focused light reaches the required intensities and that scattered light does not cause excitation of the fluorophore.
The majority of pulse broadening in ultrashort pulse lasers is caused by the positive group-velocity dispersion of the gain medium. Other intracavity elements such as prisms will also contribute positive dispersion. To obtain the shortest possible pulses from the laser cavity the overall GVD has to be near zero. A practical method for doing this is to introduce pairs of prisms into the cavity, as described by Fork et al. in 1984 . This is known as dispersion compensation. The prism material will itself contribute positive dispersion, but it is possible to configure the prism pairs so that the overall contribution is negative (see Fig. 1). Kang et al.  generate negative group velocity dispersion by a single prism and wedge mirror in femtosecond lasers. They discuss that both theoretical analyses and the experimental results show that the GVD is directly proportional to the distance between the prism and the Ti:sapphire crystal. Also they prove that the amount of GVD generated by this method approach that generated by a pair of prisms. Andreas et al.  used dielectric mirrors for group-delay dispersion control of s laser cavity free from the problems of cubic dispersion, asymmetric spectra and increased sensitivity of pulse width to cavity and prism alignment. By use of Kerr-lens mode locked Ti:sapphire laser without any intracavity prisms for generating highly stable optical pulses as short as 11 fs. Recently Zeng et al. [8, 9] introduce a single prism before the two dimensional acousto-optical deflector (AOD) to allows simultaneous compensation of spatial and temporal dispersion for two-dimensional scanning.
Figure 2, 3, and the additional files 1 and 2, show the leaf structure of duckweed Lemna minuta excited by laser beam without and with using GL polarizer. In Figure 3 and the additional file 2, we note a considerable enhancing with using the GL polarizer, and we can see the details of the leaf structure in early stages when we trying to get focus through z-stacks of images going though the leaf from the dorsal surface to ventral surface in comparison to the exactly the same measurements without using GL polarizer. In this case we can see the structure of the leaf (which we saw it in the first slices with using GL polarizer) approximately after 15 slices, i.e we have to go deeply inside the sample about 7.5 μm (separation between the slices is 0.5 μm) before using the GL polarizer. Hence, with this modification we able to reduce the time of exposure the sample to the laser radiation thereby we will reduce the probability of photobleaching and phototoxicity. If we look at Figure 2 and the additional file 1, we note that without using the GL polarizer the images will be blurred and we need more focusing to get clearer images resulting to exposure the sample more time to the laser radiation. This improvement over the normal 2PLSM will enable us to get quick focus through the sample with high resolution and give us more opportunity to go deeply in side the tissue to see clearer details structures with less damage to the living cells. We provided two movies (additional files 1 and 2) which show the leaf structures with and without using GL polarizer. These movies clearly show the resolution enhancement with GL polarizer. 2b1af7f3a8