The warbleR function lspec produces image files with spectrograms of whole recordings split into multiple rows. For a long recording several image files will be produced, which could be inconvenient when dealing with many long recordings. I recently added a new function lspec2pdf that combines lspec images in .jpeg format into a single pdf file (available in warbleR 1.1.5 or higher).

You need warbleR version 1.1.5 or higher to be able to run the code (currently you have to download it from github using the package devtools).

#run it only if devtools isn't installed
install.packages("devtools")

devtools::install_github("maRce10/warbleR")
require("warbleR")

Download a couple of long recordings (> 2 min) from xeno-canto and convert them to .wav format

rec1 <- querxc(qword = 'nr:153989', download = TRUE)
## 
   |++++++++++++++++++++++++++++++++++++++++++++++++++| 100% elapsed = 00s
## 
   |++++++++++++++++++++++++++++++++++++++++++++++++++| 100% elapsed = 17s
rec2 <- querxc(qword = 'nr:154190', download = TRUE)
## 
   |++++++++++++++++++++++++++++++++++++++++++++++++++| 100% elapsed = 00s
## 
   |++++++++++++++++++++++++++++++++++++++++++++++++++| 100% elapsed = 17s
mp32wav()
## 
   |+++++++++++++++++++++++++                         | 50% ~01s          
   |++++++++++++++++++++++++++++++++++++++++++++++++++| 100% elapsed = 02s

Create the long spectrograms in .jpeg format

lspec(flim = c(0, 6), sxrow = 10, pal = reverse.heat.colors, wl = 200, it = "jpeg")
## 
   |+++++++++++++++++++++++++                         | 50% ~10s
## 
   |++++++++++++++++++++++++++++++++++++++++++++++++++| 100% elapsed = 24s

And the last step is to create a single pdf file for each sound file. Note that the keep.jpeg argument allows to remove the .jpeg files (when set to FALSE)

lspec2pdf(keep.jpeg = FALSE)
## 
   |+++++++++++++++++++++++++                         | 50% ~01s
## 
   |++++++++++++++++++++++++++++++++++++++++++++++++++| 100% elapsed = 03s

You should get 2 pdf files that look like this one