lavfi: add const to the AVFilter parameter of avfilter_graph_create_filter()

This function should never modify the filter.
avconv: improve some variable names

'filter' is too generic, since the functions in question deal with
several filters.

Also add const qualifiers to those variables.
aac: Check init_get_bits return value

Some code paths can call it with invalid length.

CC: libav-stable@libav.org
aac: Forward errors properly in aac_decode_frame_int

Incidentally also remove a warning.
mxfenc: switch to av_reallocp_array() and check allocation errors

Signed-off-by: Anton Khirnov <anton@khirnov.net>
avserver: do not use a static string as a default for a string option

Fixes an invalid free.

Bug-id: 448
avconv: fix usage of deprecated lavfi API
lavfi/fifo: fix flushing when using request_samples

If any samples are still buffered when request_frame returns EOF, they
won't be returned currently.
avconv: insert extra filters in the same way for both graph inputs and outputs

This will allow using the same code when one filter can be inserted both
on input and output.
avconv: distinguish between -ss 0 and -ss not being used

Using -ss 0 to drop frames with negative timestamps is a perfectly valid
use case.
avconv: make input -ss accurate when transcoding

Insert (a)trim filters on the corresponding inputs, so the extra frames
are decoded and discarded.
avconv: support -t as an input option.

It limits the duration of the data read from a given input.
vdpau: remove old-style decoders

Signed-off-by: Anton Khirnov <anton@khirnov.net>
vdpau: deprecate old codec-specific pixel formats

Signed-off-by: Anton Khirnov <anton@khirnov.net>
vdpau: deprecate VDPAU codec capability

Signed-off-by: Anton Khirnov <anton@khirnov.net>
vdpau: store picture data in picture's rather than codec's context

Signed-off-by: Anton Khirnov <anton@khirnov.net>
vdpau: deprecate bitstream buffers within the hardware context

The bitstream buffers are now private and freed by libavcodec. For
backward compatibility, the hold bitstream buffer pointer is left NULL
(applications were supposed to av_freep() it).

Signed-off-by: Anton Khirnov <anton@khirnov.net>