| 3 | 3 | Re-encoding a 192 kb/s AAC-LC stream to 128 kb/s with either the libfdk_aac or aac_at encoders results in a stream that is 256 kb/s. The status shows ~128 kb/s until the last few seconds, then jumps up and the time index progresses slower. A trace confirms what is happening is in the last couple of seconds, there are a lot more samples of smaller size. This is probably a pathological case, but I have run across several different videos exhibiting this issue (the audio stream originates from mp4 videos). Performing a trace on a copy command from the output of each encoder shows that libfdk_aac and aac_at are inflating the size of these small samples by 100 times, whereas the native aac is preserving the original small size. |
