A signal adjustment program comprising instructions which, when the program is executed by a computer, cause the computer to carry out steps: analyzing a first video obtained by imaging an object reflecting light in which a signal changing in time series is embedded to specify an area in which the signal is embedded in an image included in the first video; adjusting the signal embedded in the area; and outputting a second video including the adjusted signal to a providing apparatus, characterized in that the adjusting includes: referring to attenuation factor information indicating reciprocals of attenuation factors corresponding to a plurality of compression schemes and a plurality of compression rates; obtaining a reciprocal of attenuation factor corresponding to a compression scheme and a compression rate of compression processing performed by the providing apparatus; calculating a first threshold for a first amplitude of the signal embedded in the area by multiplying the obtained reciprocal of the attenuation factor by a second threshold value for a second amplitude of a signal obtained by restoration processing of the providing apparatus; and increasing the first amplitude of the signal embedded in the area such that the first amplitude of the signal embedded in the area is equal to or larger than the first threshold in a case where the first amplitude of the signal embedded in the area is smaller than the first threshold. analyzing a first video obtained by imaging an object reflecting light in which a signal changing in time series is embedded to specify an area in which the signal is embedded in an image included in the first video; adjusting the signal embedded in the area; and outputting a second video including the adjusted signal to a providing apparatus, characterized in that the adjusting includes: referring to attenuation factor information indicating reciprocals of attenuation factors corresponding to a plurality of compression schemes and a plurality of compression rates; obtaining a reciprocal of attenuation factor corresponding to a compression scheme and a compression rate of compression processing performed by the providing apparatus; calculating a first threshold for a first amplitude of the signal embedded in the area by multiplying the obtained reciprocal of the attenuation factor by a second threshold value for a second amplitude of a signal obtained by restoration processing of the providing apparatus; and increasing the first amplitude of the signal embedded in the area such that the first amplitude of the signal embedded in the area is equal to or larger than the first threshold in a case where the first amplitude of the signal embedded in the area is smaller than the first threshold. characterized in that the adjusting includes: referring to attenuation factor information indicating reciprocals of attenuation factors corresponding to a plurality of compression schemes and a plurality of compression rates; obtaining a reciprocal of attenuation factor corresponding to a compression scheme and a compression rate of compression processing performed by the providing apparatus; calculating a first threshold for a first amplitude of the signal embedded in the area by multiplying the obtained reciprocal of the attenuation factor by a second threshold value for a second amplitude of a signal obtained by restoration processing of the providing apparatus; and increasing the first amplitude of the signal embedded in the area such that the first amplitude of the signal embedded in the area is equal to or larger than the first threshold in a case where the first amplitude of the signal embedded in the area is smaller than the first threshold.